pub struct String { /* fields omitted */ }
A UTF-8 encoded, growable string.
The String
type is the most common string type that has ownership over the contents of the string. It has a close relationship with its borrowed counterpart, the primitive str
.
You can create a String
from a literal string with String::from
:
let hello = String::from("Hello, world!");
You can append a char
to a String
with the push
method, and append a &str
with the push_str
method:
let mut hello = String::from("Hello, "); hello.push('w'); hello.push_str("orld!");
If you have a vector of UTF-8 bytes, you can create a String
from it with the from_utf8
method:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so we'll use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart);
String
s are always valid UTF-8. This has a few implications, the first of which is that if you need a non-UTF-8 string, consider OsString
. It is similar, but without the UTF-8 constraint. The second implication is that you cannot index into a String
:
let s = "hello"; println!("The first letter of s is {}", s[0]); // ERROR!!!
Indexing is intended to be a constant-time operation, but UTF-8 encoding does not allow us to do this. Furthermore, it's not clear what sort of thing the index should return: a byte, a codepoint, or a grapheme cluster. The bytes
and chars
methods return iterators over the first two, respectively.
String
s implement Deref
<Target=str>
, and so inherit all of str
's methods. In addition, this means that you can pass a String
to a function which takes a &str
by using an ampersand (&
):
fn takes_str(s: &str) { } let s = String::from("Hello"); takes_str(&s);
This will create a &str
from the String
and pass it in. This conversion is very inexpensive, and so generally, functions will accept &str
s as arguments unless they need a String
for some specific reason.
In certain cases Rust doesn't have enough information to make this conversion, known as Deref
coercion. In the following example a string slice &'a str
implements the trait TraitExample
, and the function example_func
takes anything that implements the trait. In this case Rust would need to make two implicit conversions, which Rust doesn't have the means to do. For that reason, the following example will not compile.
trait TraitExample {} impl<'a> TraitExample for &'a str {} fn example_func<A: TraitExample>(example_arg: A) {} let example_string = String::from("example_string"); example_func(&example_string);
There are two options that would work instead. The first would be to change the line example_func(&example_string);
to example_func(example_string.as_str());
, using the method as_str()
to explicitly extract the string slice containing the string. The second way changes example_func(&example_string);
to example_func(&*example_string);
. In this case we are dereferencing a String
to a str
, then referencing the str
back to &str
. The second way is more idiomatic, however both work to do the conversion explicitly rather than relying on the implicit conversion.
A String
is made up of three components: a pointer to some bytes, a length, and a capacity. The pointer points to an internal buffer String
uses to store its data. The length is the number of bytes currently stored in the buffer, and the capacity is the size of the buffer in bytes. As such, the length will always be less than or equal to the capacity.
This buffer is always stored on the heap.
You can look at these with the as_ptr
, len
, and capacity
methods:
use std::mem; let story = String::from("Once upon a time..."); // Prevent automatically dropping the String's data let mut story = mem::ManuallyDrop::new(story); let ptr = story.as_mut_ptr(); let len = story.len(); let capacity = story.capacity(); // story has nineteen bytes assert_eq!(19, len); // We can re-build a String out of ptr, len, and capacity. This is all // unsafe because we are responsible for making sure the components are // valid: let s = unsafe { String::from_raw_parts(ptr, len, capacity) } ; assert_eq!(String::from("Once upon a time..."), s);
If a String
has enough capacity, adding elements to it will not re-allocate. For example, consider this program:
let mut s = String::new(); println!("{}", s.capacity()); for _ in 0..5 { s.push_str("hello"); println!("{}", s.capacity()); }
This will output the following:
0 5 10 20 20 40
At first, we have no memory allocated at all, but as we append to the string, it increases its capacity appropriately. If we instead use the with_capacity
method to allocate the correct capacity initially:
let mut s = String::with_capacity(25); println!("{}", s.capacity()); for _ in 0..5 { s.push_str("hello"); println!("{}", s.capacity()); }
We end up with a different output:
25 25 25 25 25 25
Here, there's no need to allocate more memory inside the loop.
impl String
[src]
pub const fn new() -> String
[src]
Creates a new empty String
.
Given that the String
is empty, this will not allocate any initial buffer. While that means that this initial operation is very inexpensive, it may cause excessive allocation later when you add data. If you have an idea of how much data the String
will hold, consider the with_capacity
method to prevent excessive re-allocation.
Basic usage:
let s = String::new();
pub fn with_capacity(capacity: usize) -> String
[src]
Creates a new empty String
with a particular capacity.
String
s have an internal buffer to hold their data. The capacity is the length of that buffer, and can be queried with the capacity
method. This method creates an empty String
, but one with an initial buffer that can hold capacity
bytes. This is useful when you may be appending a bunch of data to the String
, reducing the number of reallocations it needs to do.
If the given capacity is 0
, no allocation will occur, and this method is identical to the new
method.
Basic usage:
let mut s = String::with_capacity(10); // The String contains no chars, even though it has capacity for more assert_eq!(s.len(), 0); // These are all done without reallocating... let cap = s.capacity(); for _ in 0..10 { s.push('a'); } assert_eq!(s.capacity(), cap); // ...but this may make the string reallocate s.push('a');
pub fn from_utf8(vec: Vec<u8>) -> Result<String, FromUtf8Error>
[src]
Converts a vector of bytes to a String
.
A string (String
) is made of bytes (u8
), and a vector of bytes (Vec<u8>
) is made of bytes, so this function converts between the two. Not all byte slices are valid String
s, however: String
requires that it is valid UTF-8. from_utf8()
checks to ensure that the bytes are valid UTF-8, and then does the conversion.
If you are sure that the byte slice is valid UTF-8, and you don't want to incur the overhead of the validity check, there is an unsafe version of this function, from_utf8_unchecked
, which has the same behavior but skips the check.
This method will take care to not copy the vector, for efficiency's sake.
If you need a &str
instead of a String
, consider str::from_utf8
.
The inverse of this method is into_bytes
.
Returns Err
if the slice is not UTF-8 with a description as to why the provided bytes are not UTF-8. The vector you moved in is also included.
Basic usage:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; // We know these bytes are valid, so we'll use `unwrap()`. let sparkle_heart = String::from_utf8(sparkle_heart).unwrap(); assert_eq!("💖", sparkle_heart);
Incorrect bytes:
// some invalid bytes, in a vector let sparkle_heart = vec![0, 159, 146, 150]; assert!(String::from_utf8(sparkle_heart).is_err());
See the docs for FromUtf8Error
for more details on what you can do with this error.
pub fn from_utf8_lossy(v: &[u8]) -> Cow<'_, str>
[src]
Converts a slice of bytes to a string, including invalid characters.
Strings are made of bytes (u8
), and a slice of bytes (&[u8]
) is made of bytes, so this function converts between the two. Not all byte slices are valid strings, however: strings are required to be valid UTF-8. During this conversion, from_utf8_lossy()
will replace any invalid UTF-8 sequences with U+FFFD REPLACEMENT CHARACTER
, which looks like this: �
If you are sure that the byte slice is valid UTF-8, and you don't want to incur the overhead of the conversion, there is an unsafe version of this function, from_utf8_unchecked
, which has the same behavior but skips the checks.
This function returns a Cow<'a, str>
. If our byte slice is invalid UTF-8, then we need to insert the replacement characters, which will change the size of the string, and hence, require a String
. But if it's already valid UTF-8, we don't need a new allocation. This return type allows us to handle both cases.
Basic usage:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; let sparkle_heart = String::from_utf8_lossy(&sparkle_heart); assert_eq!("💖", sparkle_heart);
Incorrect bytes:
// some invalid bytes let input = b"Hello \xF0\x90\x80World"; let output = String::from_utf8_lossy(input); assert_eq!("Hello �World", output);
pub fn from_utf16(v: &[u16]) -> Result<String, FromUtf16Error>
[src]
Decode a UTF-16 encoded vector v
into a String
, returning Err
if v
contains any invalid data.
Basic usage:
// 𝄞music let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063]; assert_eq!(String::from("𝄞music"), String::from_utf16(v).unwrap()); // 𝄞mu<invalid>ic let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063]; assert!(String::from_utf16(v).is_err());
pub fn from_utf16_lossy(v: &[u16]) -> String
[src]
Decode a UTF-16 encoded slice v
into a String
, replacing invalid data with the replacement character (U+FFFD
).
Unlike from_utf8_lossy
which returns a Cow<'a, str>
, from_utf16_lossy
returns a String
since the UTF-16 to UTF-8 conversion requires a memory allocation.
Basic usage:
// 𝄞mus<invalid>ic<invalid> let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834]; assert_eq!(String::from("𝄞mus\u{FFFD}ic\u{FFFD}"), String::from_utf16_lossy(v));
pub fn into_raw_parts(self) -> (*mut u8, usize, usize)
[src]
Decomposes a String
into its raw components.
Returns the raw pointer to the underlying data, the length of the string (in bytes), and the allocated capacity of the data (in bytes). These are the same arguments in the same order as the arguments to from_raw_parts
.
After calling this function, the caller is responsible for the memory previously managed by the String
. The only way to do this is to convert the raw pointer, length, and capacity back into a String
with the from_raw_parts
function, allowing the destructor to perform the cleanup.
#![feature(vec_into_raw_parts)] let s = String::from("hello"); let (ptr, len, cap) = s.into_raw_parts(); let rebuilt = unsafe { String::from_raw_parts(ptr, len, cap) }; assert_eq!(rebuilt, "hello");
pub unsafe fn from_raw_parts(
buf: *mut u8,
length: usize,
capacity: usize
) -> String
[src]
Creates a new String
from a length, capacity, and pointer.
This is highly unsafe, due to the number of invariants that aren't checked:
buf
needs to have been previously allocated by the same allocator the standard library uses, with a required alignment of exactly 1.length
needs to be less than or equal to capacity
.capacity
needs to be the correct value.length
bytes at buf
need to be valid UTF-8.Violating these may cause problems like corrupting the allocator's internal data structures.
The ownership of buf
is effectively transferred to the String
which may then deallocate, reallocate or change the contents of memory pointed to by the pointer at will. Ensure that nothing else uses the pointer after calling this function.
Basic usage:
use std::mem; unsafe { let s = String::from("hello"); // Prevent automatically dropping the String's data let mut s = mem::ManuallyDrop::new(s); let ptr = s.as_mut_ptr(); let len = s.len(); let capacity = s.capacity(); let s = String::from_raw_parts(ptr, len, capacity); assert_eq!(String::from("hello"), s); }
pub unsafe fn from_utf8_unchecked(bytes: Vec<u8>) -> String
[src]
Converts a vector of bytes to a String
without checking that the string contains valid UTF-8.
See the safe version, from_utf8
, for more details.
This function is unsafe because it does not check that the bytes passed to it are valid UTF-8. If this constraint is violated, it may cause memory unsafety issues with future users of the String
, as the rest of the standard library assumes that String
s are valid UTF-8.
Basic usage:
// some bytes, in a vector let sparkle_heart = vec![240, 159, 146, 150]; let sparkle_heart = unsafe { String::from_utf8_unchecked(sparkle_heart) }; assert_eq!("💖", sparkle_heart);
pub fn into_bytes(self) -> Vec<u8>ⓘNotable traits for Vec<u8>
impl Write for Vec<u8>
[src]
Converts a String
into a byte vector.
This consumes the String
, so we do not need to copy its contents.
Basic usage:
let s = String::from("hello"); let bytes = s.into_bytes(); assert_eq!(&[104, 101, 108, 108, 111][..], &bytes[..]);
pub fn as_str(&self) -> &str
[src]1.7.0
Extracts a string slice containing the entire String
.
Basic usage:
let s = String::from("foo"); assert_eq!("foo", s.as_str());
pub fn as_mut_str(&mut self) -> &mut str
[src]1.7.0
Converts a String
into a mutable string slice.
Basic usage:
let mut s = String::from("foobar"); let s_mut_str = s.as_mut_str(); s_mut_str.make_ascii_uppercase(); assert_eq!("FOOBAR", s_mut_str);
pub fn push_str(&mut self, string: &str)
[src]
Appends a given string slice onto the end of this String
.
Basic usage:
let mut s = String::from("foo"); s.push_str("bar"); assert_eq!("foobar", s);
pub fn capacity(&self) -> usize
[src]
Returns this String
's capacity, in bytes.
Basic usage:
let s = String::with_capacity(10); assert!(s.capacity() >= 10);
pub fn reserve(&mut self, additional: usize)
[src]
Ensures that this String
's capacity is at least additional
bytes larger than its length.
The capacity may be increased by more than additional
bytes if it chooses, to prevent frequent reallocations.
If you do not want this "at least" behavior, see the reserve_exact
method.
Panics if the new capacity overflows usize
.
Basic usage:
let mut s = String::new(); s.reserve(10); assert!(s.capacity() >= 10);
This may not actually increase the capacity:
let mut s = String::with_capacity(10); s.push('a'); s.push('b'); // s now has a length of 2 and a capacity of 10 assert_eq!(2, s.len()); assert_eq!(10, s.capacity()); // Since we already have an extra 8 capacity, calling this... s.reserve(8); // ... doesn't actually increase. assert_eq!(10, s.capacity());
pub fn reserve_exact(&mut self, additional: usize)
[src]
Ensures that this String
's capacity is additional
bytes larger than its length.
Consider using the reserve
method unless you absolutely know better than the allocator.
Panics if the new capacity overflows usize
.
Basic usage:
let mut s = String::new(); s.reserve_exact(10); assert!(s.capacity() >= 10);
This may not actually increase the capacity:
let mut s = String::with_capacity(10); s.push('a'); s.push('b'); // s now has a length of 2 and a capacity of 10 assert_eq!(2, s.len()); assert_eq!(10, s.capacity()); // Since we already have an extra 8 capacity, calling this... s.reserve_exact(8); // ... doesn't actually increase. assert_eq!(10, s.capacity());
pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>
[src]
Tries to reserve capacity for at least additional
more elements to be inserted in the given String
. The collection may reserve more space to avoid frequent reallocations. After calling reserve
, capacity will be greater than or equal to self.len() + additional
. Does nothing if capacity is already sufficient.
If the capacity overflows, or the allocator reports a failure, then an error is returned.
#![feature(try_reserve)] use std::collections::TryReserveError; fn process_data(data: &str) -> Result<String, TryReserveError> { let mut output = String::new(); // Pre-reserve the memory, exiting if we can't output.try_reserve(data.len())?; // Now we know this can't OOM in the middle of our complex work output.push_str(data); Ok(output) }
pub fn try_reserve_exact(
&mut self,
additional: usize
) -> Result<(), TryReserveError>
[src]
Tries to reserves the minimum capacity for exactly additional
more elements to be inserted in the given String
. After calling reserve_exact
, capacity will be greater than or equal to self.len() + additional
. Does nothing if the capacity is already sufficient.
Note that the allocator may give the collection more space than it requests. Therefore, capacity can not be relied upon to be precisely minimal. Prefer reserve
if future insertions are expected.
If the capacity overflows, or the allocator reports a failure, then an error is returned.
#![feature(try_reserve)] use std::collections::TryReserveError; fn process_data(data: &str) -> Result<String, TryReserveError> { let mut output = String::new(); // Pre-reserve the memory, exiting if we can't output.try_reserve(data.len())?; // Now we know this can't OOM in the middle of our complex work output.push_str(data); Ok(output) }
pub fn shrink_to_fit(&mut self)
[src]
Shrinks the capacity of this String
to match its length.
Basic usage:
let mut s = String::from("foo"); s.reserve(100); assert!(s.capacity() >= 100); s.shrink_to_fit(); assert_eq!(3, s.capacity());
pub fn shrink_to(&mut self, min_capacity: usize)
[src]
Shrinks the capacity of this String
with a lower bound.
The capacity will remain at least as large as both the length and the supplied value.
Panics if the current capacity is smaller than the supplied minimum capacity.
#![feature(shrink_to)] let mut s = String::from("foo"); s.reserve(100); assert!(s.capacity() >= 100); s.shrink_to(10); assert!(s.capacity() >= 10); s.shrink_to(0); assert!(s.capacity() >= 3);
pub fn push(&mut self, ch: char)
[src]
Appends the given char
to the end of this String
.
Basic usage:
let mut s = String::from("abc"); s.push('1'); s.push('2'); s.push('3'); assert_eq!("abc123", s);
pub fn as_bytes(&self) -> &[u8]ⓘNotable traits for &'_ [u8]
impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
[src]
Returns a byte slice of this String
's contents.
The inverse of this method is from_utf8
.
Basic usage:
let s = String::from("hello"); assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());
pub fn truncate(&mut self, new_len: usize)
[src]
Shortens this String
to the specified length.
If new_len
is greater than the string's current length, this has no effect.
Note that this method has no effect on the allocated capacity of the string
Panics if new_len
does not lie on a char
boundary.
Basic usage:
let mut s = String::from("hello"); s.truncate(2); assert_eq!("he", s);
pub fn pop(&mut self) -> Option<char>
[src]
Removes the last character from the string buffer and returns it.
Returns None
if this String
is empty.
Basic usage:
let mut s = String::from("foo"); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('o')); assert_eq!(s.pop(), Some('f')); assert_eq!(s.pop(), None);
pub fn remove(&mut self, idx: usize) -> char
[src]
Removes a char
from this String
at a byte position and returns it.
This is an O(n) operation, as it requires copying every element in the buffer.
Panics if idx
is larger than or equal to the String
's length, or if it does not lie on a char
boundary.
Basic usage:
let mut s = String::from("foo"); assert_eq!(s.remove(0), 'f'); assert_eq!(s.remove(1), 'o'); assert_eq!(s.remove(0), 'o');
pub fn retain<F>(&mut self, f: F) where
F: FnMut(char) -> bool,
[src]1.26.0
Retains only the characters specified by the predicate.
In other words, remove all characters c
such that f(c)
returns false
. This method operates in place, visiting each character exactly once in the original order, and preserves the order of the retained characters.
let mut s = String::from("f_o_ob_ar"); s.retain(|c| c != '_'); assert_eq!(s, "foobar");
The exact order may be useful for tracking external state, like an index.
let mut s = String::from("abcde"); let keep = [false, true, true, false, true]; let mut i = 0; s.retain(|_| (keep[i], i += 1).0); assert_eq!(s, "bce");
pub fn insert(&mut self, idx: usize, ch: char)
[src]
Inserts a character into this String
at a byte position.
This is an O(n) operation as it requires copying every element in the buffer.
Panics if idx
is larger than the String
's length, or if it does not lie on a char
boundary.
Basic usage:
let mut s = String::with_capacity(3); s.insert(0, 'f'); s.insert(1, 'o'); s.insert(2, 'o'); assert_eq!("foo", s);
pub fn insert_str(&mut self, idx: usize, string: &str)
[src]1.16.0
Inserts a string slice into this String
at a byte position.
This is an O(n) operation as it requires copying every element in the buffer.
Panics if idx
is larger than the String
's length, or if it does not lie on a char
boundary.
Basic usage:
let mut s = String::from("bar"); s.insert_str(0, "foo"); assert_eq!("foobar", s);
pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8>ⓘNotable traits for Vec<u8>
impl Write for Vec<u8>
[src]
Returns a mutable reference to the contents of this String
.
This function is unsafe because it does not check that the bytes passed to it are valid UTF-8. If this constraint is violated, it may cause memory unsafety issues with future users of the String
, as the rest of the standard library assumes that String
s are valid UTF-8.
Basic usage:
let mut s = String::from("hello"); unsafe { let vec = s.as_mut_vec(); assert_eq!(&[104, 101, 108, 108, 111][..], &vec[..]); vec.reverse(); } assert_eq!(s, "olleh");
pub fn len(&self) -> usize
[src]
Returns the length of this String
, in bytes, not char
s or graphemes. In other words, it may not be what a human considers the length of the string.
Basic usage:
let a = String::from("foo"); assert_eq!(a.len(), 3); let fancy_f = String::from("ƒoo"); assert_eq!(fancy_f.len(), 4); assert_eq!(fancy_f.chars().count(), 3);
pub fn is_empty(&self) -> bool
[src]
Returns true
if this String
has a length of zero, and false
otherwise.
Basic usage:
let mut v = String::new(); assert!(v.is_empty()); v.push('a'); assert!(!v.is_empty());
#[must_use = "use `.truncate()` if you don't need the other half"]pub fn split_off(&mut self, at: usize) -> String
[src]1.16.0
Splits the string into two at the given index.
Returns a newly allocated String
. self
contains bytes [0, at)
, and the returned String
contains bytes [at, len)
. at
must be on the boundary of a UTF-8 code point.
Note that the capacity of self
does not change.
Panics if at
is not on a UTF-8
code point boundary, or if it is beyond the last code point of the string.
let mut hello = String::from("Hello, World!"); let world = hello.split_off(7); assert_eq!(hello, "Hello, "); assert_eq!(world, "World!");
pub fn clear(&mut self)
[src]
Truncates this String
, removing all contents.
While this means the String
will have a length of zero, it does not touch its capacity.
Basic usage:
let mut s = String::from("foo"); s.clear(); assert!(s.is_empty()); assert_eq!(0, s.len()); assert_eq!(3, s.capacity());
pub fn drain<R>(&mut self, range: R) -> Drain<'_>ⓘNotable traits for Drain<'_>
impl<'_> Iterator for Drain<'_>
type Item = char;
where
R: RangeBounds<usize>,
[src]1.6.0
Creates a draining iterator that removes the specified range in the String
and yields the removed chars
.
Note: The element range is removed even if the iterator is not consumed until the end.
Panics if the starting point or end point do not lie on a char
boundary, or if they're out of bounds.
Basic usage:
let mut s = String::from("α is alpha, β is beta"); let beta_offset = s.find('β').unwrap_or(s.len()); // Remove the range up until the β from the string let t: String = s.drain(..beta_offset).collect(); assert_eq!(t, "α is alpha, "); assert_eq!(s, "β is beta"); // A full range clears the string s.drain(..); assert_eq!(s, "");
pub fn replace_range<R>(&mut self, range: R, replace_with: &str) where
R: RangeBounds<usize>,
[src]1.27.0
Removes the specified range in the string, and replaces it with the given string. The given string doesn't need to be the same length as the range.
Panics if the starting point or end point do not lie on a char
boundary, or if they're out of bounds.
Basic usage:
let mut s = String::from("α is alpha, β is beta"); let beta_offset = s.find('β').unwrap_or(s.len()); // Replace the range up until the β from the string s.replace_range(..beta_offset, "Α is capital alpha; "); assert_eq!(s, "Α is capital alpha; β is beta");
pub fn into_boxed_str(self) -> Box<str>ⓘNotable traits for Box<F>
impl<F> Future for Box<F> where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<I> Iterator for Box<I> where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized> Read for Box<R>
impl<W: Write + ?Sized> Write for Box<W>
[src]1.4.0
Converts this String
into a Box
<
str
>
.
This will drop any excess capacity.
Basic usage:
let s = String::from("hello"); let b = s.into_boxed_str();
pub const fn len(&self) -> usize
[src]
Returns the length of self
.
This length is in bytes, not char
s or graphemes. In other words, it may not be what a human considers the length of the string.
Basic usage:
let len = "foo".len(); assert_eq!(3, len); assert_eq!("ƒoo".len(), 4); // fancy f! assert_eq!("ƒoo".chars().count(), 3);
pub const fn is_empty(&self) -> bool
[src]
Returns true
if self
has a length of zero bytes.
Basic usage:
let s = ""; assert!(s.is_empty()); let s = "not empty"; assert!(!s.is_empty());
pub fn is_char_boundary(&self, index: usize) -> bool
[src]1.9.0
Checks that index
-th byte is the first byte in a UTF-8 code point sequence or the end of the string.
The start and end of the string (when index == self.len()
) are considered to be boundaries.
Returns false
if index
is greater than self.len()
.
let s = "Löwe 老虎 Léopard"; assert!(s.is_char_boundary(0)); // start of `老` assert!(s.is_char_boundary(6)); assert!(s.is_char_boundary(s.len())); // second byte of `ö` assert!(!s.is_char_boundary(2)); // third byte of `老` assert!(!s.is_char_boundary(8));
pub const fn as_bytes(&self) -> &[u8]ⓘNotable traits for &'_ [u8]
impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
[src]
Converts a string slice to a byte slice. To convert the byte slice back into a string slice, use the from_utf8
function.
Basic usage:
let bytes = "bors".as_bytes(); assert_eq!(b"bors", bytes);
pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8]ⓘNotable traits for &'_ [u8]
impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
[src]1.20.0
Converts a mutable string slice to a mutable byte slice.
The caller must ensure that the content of the slice is valid UTF-8 before the borrow ends and the underlying str
is used.
Use of a str
whose contents are not valid UTF-8 is undefined behavior.
Basic usage:
let mut s = String::from("Hello"); let bytes = unsafe { s.as_bytes_mut() }; assert_eq!(b"Hello", bytes);
Mutability:
let mut s = String::from("🗻∈🌏"); unsafe { let bytes = s.as_bytes_mut(); bytes[0] = 0xF0; bytes[1] = 0x9F; bytes[2] = 0x8D; bytes[3] = 0x94; } assert_eq!("🍔∈🌏", s);
pub const fn as_ptr(&self) -> *const u8
[src]
Converts a string slice to a raw pointer.
As string slices are a slice of bytes, the raw pointer points to a u8
. This pointer will be pointing to the first byte of the string slice.
The caller must ensure that the returned pointer is never written to. If you need to mutate the contents of the string slice, use as_mut_ptr
.
Basic usage:
let s = "Hello"; let ptr = s.as_ptr();
pub fn as_mut_ptr(&mut self) -> *mut u8
[src]1.36.0
Converts a mutable string slice to a raw pointer.
As string slices are a slice of bytes, the raw pointer points to a u8
. This pointer will be pointing to the first byte of the string slice.
It is your responsibility to make sure that the string slice only gets modified in a way that it remains valid UTF-8.
pub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output> where
I: SliceIndex<str>,
[src]1.20.0
Returns a subslice of str
.
This is the non-panicking alternative to indexing the str
. Returns None
whenever equivalent indexing operation would panic.
let v = String::from("🗻∈🌏"); assert_eq!(Some("🗻"), v.get(0..4)); // indices not on UTF-8 sequence boundaries assert!(v.get(1..).is_none()); assert!(v.get(..8).is_none()); // out of bounds assert!(v.get(..42).is_none());
pub fn get_mut<I>(
&mut self,
i: I
) -> Option<&mut <I as SliceIndex<str>>::Output> where
I: SliceIndex<str>,
[src]1.20.0
Returns a mutable subslice of str
.
This is the non-panicking alternative to indexing the str
. Returns None
whenever equivalent indexing operation would panic.
let mut v = String::from("hello"); // correct length assert!(v.get_mut(0..5).is_some()); // out of bounds assert!(v.get_mut(..42).is_none()); assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v)); assert_eq!("hello", v); { let s = v.get_mut(0..2); let s = s.map(|s| { s.make_ascii_uppercase(); &*s }); assert_eq!(Some("HE"), s); } assert_eq!("HEllo", v);
pub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Output where
I: SliceIndex<str>,
[src]1.20.0
Returns an unchecked subslice of str
.
This is the unchecked alternative to indexing the str
.
Callers of this function are responsible that these preconditions are satisfied:
Failing that, the returned string slice may reference invalid memory or violate the invariants communicated by the str
type.
let v = "🗻∈🌏"; unsafe { assert_eq!("🗻", v.get_unchecked(0..4)); assert_eq!("∈", v.get_unchecked(4..7)); assert_eq!("🌏", v.get_unchecked(7..11)); }
pub unsafe fn get_unchecked_mut<I>(
&mut self,
i: I
) -> &mut <I as SliceIndex<str>>::Output where
I: SliceIndex<str>,
[src]1.20.0
Returns a mutable, unchecked subslice of str
.
This is the unchecked alternative to indexing the str
.
Callers of this function are responsible that these preconditions are satisfied:
Failing that, the returned string slice may reference invalid memory or violate the invariants communicated by the str
type.
let mut v = String::from("🗻∈🌏"); unsafe { assert_eq!("🗻", v.get_unchecked_mut(0..4)); assert_eq!("∈", v.get_unchecked_mut(4..7)); assert_eq!("🌏", v.get_unchecked_mut(7..11)); }
pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str
[src]
Creates a string slice from another string slice, bypassing safety checks.
This is generally not recommended, use with caution! For a safe alternative see str
and Index
.
This new slice goes from begin
to end
, including begin
but excluding end
.
To get a mutable string slice instead, see the slice_mut_unchecked
method.
Callers of this function are responsible that three preconditions are satisfied:
begin
must not exceed end
.begin
and end
must be byte positions within the string slice.begin
and end
must lie on UTF-8 sequence boundaries.Basic usage:
let s = "Löwe 老虎 Léopard"; unsafe { assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21)); } let s = "Hello, world!"; unsafe { assert_eq!("world", s.slice_unchecked(7, 12)); }
pub unsafe fn slice_mut_unchecked(
&mut self,
begin: usize,
end: usize
) -> &mut str
[src]1.5.0
Creates a string slice from another string slice, bypassing safety checks. This is generally not recommended, use with caution! For a safe alternative see str
and IndexMut
.
This new slice goes from begin
to end
, including begin
but excluding end
.
To get an immutable string slice instead, see the slice_unchecked
method.
Callers of this function are responsible that three preconditions are satisfied:
begin
must not exceed end
.begin
and end
must be byte positions within the string slice.begin
and end
must lie on UTF-8 sequence boundaries.pub fn split_at(&self, mid: usize) -> (&str, &str)
[src]1.4.0
Divide one string slice into two at an index.
The argument, mid
, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.
The two slices returned go from the start of the string slice to mid
, and from mid
to the end of the string slice.
To get mutable string slices instead, see the split_at_mut
method.
Panics if mid
is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice.
Basic usage:
let s = "Per Martin-Löf"; let (first, last) = s.split_at(3); assert_eq!("Per", first); assert_eq!(" Martin-Löf", last);
pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)
[src]1.4.0
Divide one mutable string slice into two at an index.
The argument, mid
, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.
The two slices returned go from the start of the string slice to mid
, and from mid
to the end of the string slice.
To get immutable string slices instead, see the split_at
method.
Panics if mid
is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice.
Basic usage:
let mut s = "Per Martin-Löf".to_string(); { let (first, last) = s.split_at_mut(3); first.make_ascii_uppercase(); assert_eq!("PER", first); assert_eq!(" Martin-Löf", last); } assert_eq!("PER Martin-Löf", s);
pub fn chars(&self) -> Chars<'_>ⓘNotable traits for Chars<'a>
impl<'a> Iterator for Chars<'a>
type Item = char;
[src]
Returns an iterator over the char
s of a string slice.
As a string slice consists of valid UTF-8, we can iterate through a string slice by char
. This method returns such an iterator.
It's important to remember that char
represents a Unicode Scalar Value, and may not match your idea of what a 'character' is. Iteration over grapheme clusters may be what you actually want. This functionality is not provided by Rust's standard library, check crates.io instead.
Basic usage:
let word = "goodbye"; let count = word.chars().count(); assert_eq!(7, count); let mut chars = word.chars(); assert_eq!(Some('g'), chars.next()); assert_eq!(Some('o'), chars.next()); assert_eq!(Some('o'), chars.next()); assert_eq!(Some('d'), chars.next()); assert_eq!(Some('b'), chars.next()); assert_eq!(Some('y'), chars.next()); assert_eq!(Some('e'), chars.next()); assert_eq!(None, chars.next());
Remember, char
s may not match your intuition about characters:
let y = "y̆"; let mut chars = y.chars(); assert_eq!(Some('y'), chars.next()); // not 'y̆' assert_eq!(Some('\u{0306}'), chars.next()); assert_eq!(None, chars.next());
pub fn char_indices(&self) -> CharIndices<'_>ⓘNotable traits for CharIndices<'a>
impl<'a> Iterator for CharIndices<'a>
type Item = (usize, char);
[src]
Returns an iterator over the char
s of a string slice, and their positions.
As a string slice consists of valid UTF-8, we can iterate through a string slice by char
. This method returns an iterator of both these char
s, as well as their byte positions.
The iterator yields tuples. The position is first, the char
is second.
Basic usage:
let word = "goodbye"; let count = word.char_indices().count(); assert_eq!(7, count); let mut char_indices = word.char_indices(); assert_eq!(Some((0, 'g')), char_indices.next()); assert_eq!(Some((1, 'o')), char_indices.next()); assert_eq!(Some((2, 'o')), char_indices.next()); assert_eq!(Some((3, 'd')), char_indices.next()); assert_eq!(Some((4, 'b')), char_indices.next()); assert_eq!(Some((5, 'y')), char_indices.next()); assert_eq!(Some((6, 'e')), char_indices.next()); assert_eq!(None, char_indices.next());
Remember, char
s may not match your intuition about characters:
let yes = "y̆es"; let mut char_indices = yes.char_indices(); assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆') assert_eq!(Some((1, '\u{0306}')), char_indices.next()); // note the 3 here - the last character took up two bytes assert_eq!(Some((3, 'e')), char_indices.next()); assert_eq!(Some((4, 's')), char_indices.next()); assert_eq!(None, char_indices.next());
pub fn bytes(&self) -> Bytes<'_>ⓘNotable traits for Bytes<'_>
impl<'_> Iterator for Bytes<'_>
type Item = u8;
[src]
An iterator over the bytes of a string slice.
As a string slice consists of a sequence of bytes, we can iterate through a string slice by byte. This method returns such an iterator.
Basic usage:
let mut bytes = "bors".bytes(); assert_eq!(Some(b'b'), bytes.next()); assert_eq!(Some(b'o'), bytes.next()); assert_eq!(Some(b'r'), bytes.next()); assert_eq!(Some(b's'), bytes.next()); assert_eq!(None, bytes.next());
pub fn split_whitespace(&self) -> SplitWhitespace<'_>ⓘNotable traits for SplitWhitespace<'a>
impl<'a> Iterator for SplitWhitespace<'a>
type Item = &'a str;
[src]1.1.0
Splits a string slice by whitespace.
The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of whitespace.
'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space
. If you only want to split on ASCII whitespace instead, use split_ascii_whitespace
.
Basic usage:
let mut iter = "A few words".split_whitespace(); assert_eq!(Some("A"), iter.next()); assert_eq!(Some("few"), iter.next()); assert_eq!(Some("words"), iter.next()); assert_eq!(None, iter.next());
All kinds of whitespace are considered:
let mut iter = " Mary had\ta\u{2009}little \n\t lamb".split_whitespace(); assert_eq!(Some("Mary"), iter.next()); assert_eq!(Some("had"), iter.next()); assert_eq!(Some("a"), iter.next()); assert_eq!(Some("little"), iter.next()); assert_eq!(Some("lamb"), iter.next()); assert_eq!(None, iter.next());
pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_>ⓘNotable traits for SplitAsciiWhitespace<'a>
impl<'a> Iterator for SplitAsciiWhitespace<'a>
type Item = &'a str;
[src]1.34.0
Splits a string slice by ASCII whitespace.
The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of ASCII whitespace.
To split by Unicode Whitespace
instead, use split_whitespace
.
Basic usage:
let mut iter = "A few words".split_ascii_whitespace(); assert_eq!(Some("A"), iter.next()); assert_eq!(Some("few"), iter.next()); assert_eq!(Some("words"), iter.next()); assert_eq!(None, iter.next());
All kinds of ASCII whitespace are considered:
let mut iter = " Mary had\ta little \n\t lamb".split_ascii_whitespace(); assert_eq!(Some("Mary"), iter.next()); assert_eq!(Some("had"), iter.next()); assert_eq!(Some("a"), iter.next()); assert_eq!(Some("little"), iter.next()); assert_eq!(Some("lamb"), iter.next()); assert_eq!(None, iter.next());
pub fn lines(&self) -> Lines<'_>ⓘNotable traits for Lines<'a>
impl<'a> Iterator for Lines<'a>
type Item = &'a str;
[src]
An iterator over the lines of a string, as string slices.
Lines are ended with either a newline (\n
) or a carriage return with a line feed (\r\n
).
The final line ending is optional.
Basic usage:
let text = "foo\r\nbar\n\nbaz\n"; let mut lines = text.lines(); assert_eq!(Some("foo"), lines.next()); assert_eq!(Some("bar"), lines.next()); assert_eq!(Some(""), lines.next()); assert_eq!(Some("baz"), lines.next()); assert_eq!(None, lines.next());
The final line ending isn't required:
let text = "foo\nbar\n\r\nbaz"; let mut lines = text.lines(); assert_eq!(Some("foo"), lines.next()); assert_eq!(Some("bar"), lines.next()); assert_eq!(Some(""), lines.next()); assert_eq!(Some("baz"), lines.next()); assert_eq!(None, lines.next());
pub fn lines_any(&self) -> LinesAny<'_>ⓘNotable traits for LinesAny<'a>
impl<'a> Iterator for LinesAny<'a>
type Item = &'a str;
[src]
An iterator over the lines of a string.
pub fn encode_utf16(&self) -> EncodeUtf16<'_>ⓘNotable traits for EncodeUtf16<'a>
impl<'a> Iterator for EncodeUtf16<'a>
type Item = u16;
[src]1.8.0
Returns an iterator of u16
over the string encoded as UTF-16.
Basic usage:
let text = "Zażółć gęślą jaźń"; let utf8_len = text.len(); let utf16_len = text.encode_utf16().count(); assert!(utf16_len <= utf8_len);
pub fn contains<'a, P>(&'a self, pat: P) -> bool where
P: Pattern<'a>,
[src]
Returns true
if the given pattern matches a sub-slice of this string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Basic usage:
let bananas = "bananas"; assert!(bananas.contains("nana")); assert!(!bananas.contains("apples"));
pub fn starts_with<'a, P>(&'a self, pat: P) -> bool where
P: Pattern<'a>,
[src]
Returns true
if the given pattern matches a prefix of this string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Basic usage:
let bananas = "bananas"; assert!(bananas.starts_with("bana")); assert!(!bananas.starts_with("nana"));
pub fn ends_with<'a, P>(&'a self, pat: P) -> bool where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
Returns true
if the given pattern matches a suffix of this string slice.
Returns false
if it does not.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Basic usage:
let bananas = "bananas"; assert!(bananas.ends_with("anas")); assert!(!bananas.ends_with("nana"));
pub fn find<'a, P>(&'a self, pat: P) -> Option<usize> where
P: Pattern<'a>,
[src]
Returns the byte index of the first character of this string slice that matches the pattern.
Returns None
if the pattern doesn't match.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi"; assert_eq!(s.find('L'), Some(0)); assert_eq!(s.find('é'), Some(14)); assert_eq!(s.find("pard"), Some(17));
More complex patterns using point-free style and closures:
let s = "Löwe 老虎 Léopard"; assert_eq!(s.find(char::is_whitespace), Some(5)); assert_eq!(s.find(char::is_lowercase), Some(1)); assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1)); assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));
Not finding the pattern:
let s = "Löwe 老虎 Léopard"; let x: &[_] = &['1', '2']; assert_eq!(s.find(x), None);
pub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
Returns the byte index for the first character of the rightmost match of the pattern in this string slice.
Returns None
if the pattern doesn't match.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi"; assert_eq!(s.rfind('L'), Some(13)); assert_eq!(s.rfind('é'), Some(14)); assert_eq!(s.rfind("pard"), Some(24));
More complex patterns with closures:
let s = "Löwe 老虎 Léopard"; assert_eq!(s.rfind(char::is_whitespace), Some(12)); assert_eq!(s.rfind(char::is_lowercase), Some(20));
Not finding the pattern:
let s = "Löwe 老虎 Léopard"; let x: &[_] = &['1', '2']; assert_eq!(s.rfind(x), None);
pub fn split<'a, P>(&'a self, pat: P) -> Split<'a, P>ⓘNotable traits for Split<'a, P>
impl<'a, P> Iterator for Split<'a, P> where
P: Pattern<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
[src]
An iterator over substrings of this string slice, separated by characters matched by a pattern.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator will be a DoubleEndedIterator
if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ from a forward search, the rsplit
method can be used.
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".split(' ').collect(); assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]); let v: Vec<&str> = "".split('X').collect(); assert_eq!(v, [""]); let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect(); assert_eq!(v, ["lion", "", "tiger", "leopard"]); let v: Vec<&str> = "lion::tiger::leopard".split("::").collect(); assert_eq!(v, ["lion", "tiger", "leopard"]); let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect(); assert_eq!(v, ["abc", "def", "ghi"]); let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect(); assert_eq!(v, ["lion", "tiger", "leopard"]);
A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect(); assert_eq!(v, ["abc", "def", "ghi"]);
If a string contains multiple contiguous separators, you will end up with empty strings in the output:
let x = "||||a||b|c".to_string(); let d: Vec<_> = x.split('|').collect(); assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
Contiguous separators are separated by the empty string.
let x = "(///)".to_string(); let d: Vec<_> = x.split('/').collect(); assert_eq!(d, &["(", "", "", ")"]);
Separators at the start or end of a string are neighbored by empty strings.
let d: Vec<_> = "010".split("0").collect(); assert_eq!(d, &["", "1", ""]);
When the empty string is used as a separator, it separates every character in the string, along with the beginning and end of the string.
let f: Vec<_> = "rust".split("").collect(); assert_eq!(f, &["", "r", "u", "s", "t", ""]);
Contiguous separators can lead to possibly surprising behavior when whitespace is used as the separator. This code is correct:
let x = " a b c".to_string(); let d: Vec<_> = x.split(' ').collect(); assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
It does not give you:
assert_eq!(d, &["a", "b", "c"]);
Use split_whitespace
for this behavior.
pub fn split_inclusive<'a, P>(&'a self, pat: P) -> SplitInclusive<'a, P>ⓘNotable traits for SplitInclusive<'a, P>
impl<'a, P> Iterator for SplitInclusive<'a, P> where
P: Pattern<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
[src]
An iterator over substrings of this string slice, separated by characters matched by a pattern. Differs from the iterator produced by split
in that split_inclusive
leaves the matched part as the terminator of the substring.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
#![feature(split_inclusive)] let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb." .split_inclusive('\n').collect(); assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);
If the last element of the string is matched, that element will be considered the terminator of the preceding substring. That substring will be the last item returned by the iterator.
#![feature(split_inclusive)] let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n" .split_inclusive('\n').collect(); assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);
pub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P>ⓘNotable traits for RSplit<'a, P>
impl<'a, P> Iterator for RSplit<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
An iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator
if a forward/reverse search yields the same elements.
For iterating from the front, the split
method can be used.
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect(); assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]); let v: Vec<&str> = "".rsplit('X').collect(); assert_eq!(v, [""]); let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect(); assert_eq!(v, ["leopard", "tiger", "", "lion"]); let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect(); assert_eq!(v, ["leopard", "tiger", "lion"]);
A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect(); assert_eq!(v, ["ghi", "def", "abc"]);
pub fn split_terminator<'a, P>(&'a self, pat: P) -> SplitTerminator<'a, P>ⓘNotable traits for SplitTerminator<'a, P>
impl<'a, P> Iterator for SplitTerminator<'a, P> where
P: Pattern<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
[src]
An iterator over substrings of the given string slice, separated by characters matched by a pattern.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Equivalent to split
, except that the trailing substring is skipped if empty.
This method can be used for string data that is terminated, rather than separated by a pattern.
The returned iterator will be a DoubleEndedIterator
if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ from a forward search, the rsplit_terminator
method can be used.
Basic usage:
let v: Vec<&str> = "A.B.".split_terminator('.').collect(); assert_eq!(v, ["A", "B"]); let v: Vec<&str> = "A..B..".split_terminator(".").collect(); assert_eq!(v, ["A", "", "B", ""]);
pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P>ⓘNotable traits for RSplitTerminator<'a, P>
impl<'a, P> Iterator for RSplitTerminator<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
An iterator over substrings of self
, separated by characters matched by a pattern and yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
Equivalent to split
, except that the trailing substring is skipped if empty.
This method can be used for string data that is terminated, rather than separated by a pattern.
The returned iterator requires that the pattern supports a reverse search, and it will be double ended if a forward/reverse search yields the same elements.
For iterating from the front, the split_terminator
method can be used.
let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect(); assert_eq!(v, ["B", "A"]); let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect(); assert_eq!(v, ["", "B", "", "A"]);
pub fn splitn<'a, P>(&'a self, n: usize, pat: P) -> SplitN<'a, P>ⓘNotable traits for SplitN<'a, P>
impl<'a, P> Iterator for SplitN<'a, P> where
P: Pattern<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
[src]
An iterator over substrings of the given string slice, separated by a pattern, restricted to returning at most n
items.
If n
substrings are returned, the last substring (the n
th substring) will contain the remainder of the string.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator will not be double ended, because it is not efficient to support.
If the pattern allows a reverse search, the rsplitn
method can be used.
Simple patterns:
let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect(); assert_eq!(v, ["Mary", "had", "a little lambda"]); let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect(); assert_eq!(v, ["lion", "", "tigerXleopard"]); let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect(); assert_eq!(v, ["abcXdef"]); let v: Vec<&str> = "".splitn(1, 'X').collect(); assert_eq!(v, [""]);
A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect(); assert_eq!(v, ["abc", "defXghi"]);
pub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P>ⓘNotable traits for RSplitN<'a, P>
impl<'a, P> Iterator for RSplitN<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
An iterator over substrings of this string slice, separated by a pattern, starting from the end of the string, restricted to returning at most n
items.
If n
substrings are returned, the last substring (the n
th substring) will contain the remainder of the string.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator will not be double ended, because it is not efficient to support.
For splitting from the front, the splitn
method can be used.
Simple patterns:
let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect(); assert_eq!(v, ["lamb", "little", "Mary had a"]); let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect(); assert_eq!(v, ["leopard", "tiger", "lionX"]); let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect(); assert_eq!(v, ["leopard", "lion::tiger"]);
A more complex pattern, using a closure:
let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect(); assert_eq!(v, ["ghi", "abc1def"]);
pub fn split_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)> where
P: Pattern<'a>,
[src]
Splits the string on the first occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
#![feature(str_split_once)] assert_eq!("cfg".split_once('='), None); assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo"))); assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));
pub fn rsplit_once<'a, P>(&'a self, delimiter: P) -> Option<(&'a str, &'a str)> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
#![feature(str_split_once)] assert_eq!("cfg".rsplit_once('='), None); assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo"))); assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));
pub fn matches<'a, P>(&'a self, pat: P) -> Matches<'a, P>ⓘNotable traits for Matches<'a, P>
impl<'a, P> Iterator for Matches<'a, P> where
P: Pattern<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
[src]1.2.0
An iterator over the disjoint matches of a pattern within the given string slice.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator will be a DoubleEndedIterator
if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ from a forward search, the rmatches
method can be used.
Basic usage:
let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect(); assert_eq!(v, ["abc", "abc", "abc"]); let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect(); assert_eq!(v, ["1", "2", "3"]);
pub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P>ⓘNotable traits for RMatches<'a, P>
impl<'a, P> Iterator for RMatches<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
type Item = &'a str;
where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]1.2.0
An iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator
if a forward/reverse search yields the same elements.
For iterating from the front, the matches
method can be used.
Basic usage:
let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect(); assert_eq!(v, ["abc", "abc", "abc"]); let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect(); assert_eq!(v, ["3", "2", "1"]);
pub fn match_indices<'a, P>(&'a self, pat: P) -> MatchIndices<'a, P>ⓘNotable traits for MatchIndices<'a, P>
impl<'a, P> Iterator for MatchIndices<'a, P> where
P: Pattern<'a>,
type Item = (usize, &'a str);
where
P: Pattern<'a>,
[src]1.5.0
An iterator over the disjoint matches of a pattern within this string slice as well as the index that the match starts at.
For matches of pat
within self
that overlap, only the indices corresponding to the first match are returned.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator will be a DoubleEndedIterator
if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char
, but not for &str
.
If the pattern allows a reverse search but its results might differ from a forward search, the rmatch_indices
method can be used.
Basic usage:
let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect(); assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]); let v: Vec<_> = "1abcabc2".match_indices("abc").collect(); assert_eq!(v, [(1, "abc"), (4, "abc")]); let v: Vec<_> = "ababa".match_indices("aba").collect(); assert_eq!(v, [(0, "aba")]); // only the first `aba`
pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P>ⓘNotable traits for RMatchIndices<'a, P>
impl<'a, P> Iterator for RMatchIndices<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
type Item = (usize, &'a str);
where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]1.5.0
An iterator over the disjoint matches of a pattern within self
, yielded in reverse order along with the index of the match.
For matches of pat
within self
that overlap, only the indices corresponding to the last match are returned.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator
if a forward/reverse search yields the same elements.
For iterating from the front, the match_indices
method can be used.
Basic usage:
let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect(); assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]); let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect(); assert_eq!(v, [(4, "abc"), (1, "abc")]); let v: Vec<_> = "ababa".rmatch_indices("aba").collect(); assert_eq!(v, [(2, "aba")]); // only the last `aba`
#[must_use =
"this returns the trimmed string as a slice, \
without modifying the original"]pub fn trim(&self) -> &str
[src]
Returns a string slice with leading and trailing whitespace removed.
'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space
.
Basic usage:
let s = " Hello\tworld\t"; assert_eq!("Hello\tworld", s.trim());
#[must_use =
"this returns the trimmed string as a new slice, \
without modifying the original"]pub fn trim_start(&self) -> &str
[src]1.30.0
Returns a string slice with leading whitespace removed.
'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space
.
A string is a sequence of bytes. start
in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.
Basic usage:
let s = " Hello\tworld\t"; assert_eq!("Hello\tworld\t", s.trim_start());
Directionality:
let s = " English "; assert!(Some('E') == s.trim_start().chars().next()); let s = " עברית "; assert!(Some('ע') == s.trim_start().chars().next());
#[must_use =
"this returns the trimmed string as a new slice, \
without modifying the original"]pub fn trim_end(&self) -> &str
[src]1.30.0
Returns a string slice with trailing whitespace removed.
'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space
.
A string is a sequence of bytes. end
in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.
Basic usage:
let s = " Hello\tworld\t"; assert_eq!(" Hello\tworld", s.trim_end());
Directionality:
let s = " English "; assert!(Some('h') == s.trim_end().chars().rev().next()); let s = " עברית "; assert!(Some('ת') == s.trim_end().chars().rev().next());
pub fn trim_left(&self) -> &str
[src]
Returns a string slice with leading whitespace removed.
'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space
.
A string is a sequence of bytes. 'Left' in this context means the first position of that byte string; for a language like Arabic or Hebrew which are 'right to left' rather than 'left to right', this will be the right side, not the left.
Basic usage:
let s = " Hello\tworld\t"; assert_eq!("Hello\tworld\t", s.trim_left());
Directionality:
let s = " English"; assert!(Some('E') == s.trim_left().chars().next()); let s = " עברית"; assert!(Some('ע') == s.trim_left().chars().next());
pub fn trim_right(&self) -> &str
[src]
Returns a string slice with trailing whitespace removed.
'Whitespace' is defined according to the terms of the Unicode Derived Core Property White_Space
.
A string is a sequence of bytes. 'Right' in this context means the last position of that byte string; for a language like Arabic or Hebrew which are 'right to left' rather than 'left to right', this will be the left side, not the right.
Basic usage:
let s = " Hello\tworld\t"; assert_eq!(" Hello\tworld", s.trim_right());
Directionality:
let s = "English "; assert!(Some('h') == s.trim_right().chars().rev().next()); let s = "עברית "; assert!(Some('ת') == s.trim_right().chars().rev().next());
#[must_use =
"this returns the trimmed string as a new slice, \
without modifying the original"]pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: DoubleEndedSearcher<'a>,
[src]
Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.
The pattern can be a char
, a slice of char
s, or a function or closure that determines if a character matches.
Simple patterns:
assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar"); assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar"); let x: &[_] = &['1', '2']; assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");
A more complex pattern, using a closure:
assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");
#[must_use =
"this returns the trimmed string as a new slice, \
without modifying the original"]pub fn trim_start_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
[src]1.30.0
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
A string is a sequence of bytes. start
in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.
Basic usage:
assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11"); assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123"); let x: &[_] = &['1', '2']; assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");
#[must_use =
"this returns the remaining substring as a new slice, \
without modifying the original"]pub fn strip_prefix<'a, P>(&'a self, prefix: P) -> Option<&'a str> where
P: Pattern<'a>,
[src]1.45.0
Returns a string slice with the prefix removed.
If the string starts with the pattern prefix
, Some
is returned with the substring where the prefix is removed. Unlike trim_start_matches
, this method removes the prefix exactly once.
If the string does not start with prefix
, None
is returned.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar")); assert_eq!("foo:bar".strip_prefix("bar"), None); assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));
#[must_use =
"this returns the remaining substring as a new slice, \
without modifying the original"]pub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]1.45.0
Returns a string slice with the suffix removed.
If the string ends with the pattern suffix
, Some
is returned with the substring where the suffix is removed. Unlike trim_end_matches
, this method removes the suffix exactly once.
If the string does not end with suffix
, None
is returned.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar")); assert_eq!("bar:foo".strip_suffix("bar"), None); assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));
#[must_use =
"this returns the trimmed string as a new slice, \
without modifying the original"]pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]1.30.0
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
A string is a sequence of bytes. end
in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.
Simple patterns:
assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar"); assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar"); let x: &[_] = &['1', '2']; assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");
A more complex pattern, using a closure:
assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");
pub fn trim_left_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
[src]
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
A string is a sequence of bytes. 'Left' in this context means the first position of that byte string; for a language like Arabic or Hebrew which are 'right to left' rather than 'left to right', this will be the right side, not the left.
Basic usage:
assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11"); assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123"); let x: &[_] = &['1', '2']; assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");
pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
[src]
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str
, char
, a slice of char
s, or a function or closure that determines if a character matches.
A string is a sequence of bytes. 'Right' in this context means the last position of that byte string; for a language like Arabic or Hebrew which are 'right to left' rather than 'left to right', this will be the left side, not the right.
Simple patterns:
assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar"); assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar"); let x: &[_] = &['1', '2']; assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");
A more complex pattern, using a closure:
assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");
pub fn parse<F>(&self) -> Result<F, <F as FromStr>::Err> where
F: FromStr,
[src]
Parses this string slice into another type.
Because parse
is so general, it can cause problems with type inference. As such, parse
is one of the few times you'll see the syntax affectionately known as the 'turbofish': ::<>
. This helps the inference algorithm understand specifically which type you're trying to parse into.
parse
can parse any type that implements the FromStr
trait.
Will return Err
if it's not possible to parse this string slice into the desired type.
Basic usage
let four: u32 = "4".parse().unwrap(); assert_eq!(4, four);
Using the 'turbofish' instead of annotating four
:
let four = "4".parse::<u32>(); assert_eq!(Ok(4), four);
Failing to parse:
let nope = "j".parse::<u32>(); assert!(nope.is_err());
pub fn is_ascii(&self) -> bool
[src]1.23.0
Checks if all characters in this string are within the ASCII range.
let ascii = "hello!\n"; let non_ascii = "Grüße, Jürgen ❤"; assert!(ascii.is_ascii()); assert!(!non_ascii.is_ascii());
pub fn eq_ignore_ascii_case(&self, other: &str) -> bool
[src]1.23.0
Checks that two strings are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b)
, but without allocating and copying temporaries.
assert!("Ferris".eq_ignore_ascii_case("FERRIS")); assert!("Ferrös".eq_ignore_ascii_case("FERRöS")); assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));
pub fn make_ascii_uppercase(&mut self)
[src]1.23.0
Converts this string to its ASCII upper case equivalent in-place.
ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use to_ascii_uppercase
.
let mut s = String::from("Grüße, Jürgen ❤"); s.make_ascii_uppercase(); assert_eq!("GRüßE, JüRGEN ❤", s);
pub fn make_ascii_lowercase(&mut self)
[src]1.23.0
Converts this string to its ASCII lower case equivalent in-place.
ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use to_ascii_lowercase
.
let mut s = String::from("GRÜßE, JÜRGEN ❤"); s.make_ascii_lowercase(); assert_eq!("grÜße, jÜrgen ❤", s);
pub fn escape_debug(&self) -> EscapeDebug<'_>ⓘNotable traits for EscapeDebug<'a>
impl<'a> Iterator for EscapeDebug<'a>
type Item = char;
[src]1.34.0
Return an iterator that escapes each char in self
with char::escape_debug
.
Note: only extended grapheme codepoints that begin the string will be escaped.
As an iterator:
for c in "❤\n!".escape_debug() { print!("{}", c); } println!();
Using println!
directly:
println!("{}", "❤\n!".escape_debug());
Both are equivalent to:
println!("❤\\n!");
Using to_string
:
assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");
pub fn escape_default(&self) -> EscapeDefault<'_>ⓘNotable traits for EscapeDefault<'a>
impl<'a> Iterator for EscapeDefault<'a>
type Item = char;
[src]1.34.0
Return an iterator that escapes each char in self
with char::escape_default
.
As an iterator:
for c in "❤\n!".escape_default() { print!("{}", c); } println!();
Using println!
directly:
println!("{}", "❤\n!".escape_default());
Both are equivalent to:
println!("\\u{{2764}}\\n!");
Using to_string
:
assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");
pub fn escape_unicode(&self) -> EscapeUnicode<'_>ⓘNotable traits for EscapeUnicode<'a>
impl<'a> Iterator for EscapeUnicode<'a>
type Item = char;
[src]1.34.0
Return an iterator that escapes each char in self
with char::escape_unicode
.
As an iterator:
for c in "❤\n!".escape_unicode() { print!("{}", c); } println!();
Using println!
directly:
println!("{}", "❤\n!".escape_unicode());
Both are equivalent to:
println!("\\u{{2764}}\\u{{a}}\\u{{21}}");
Using to_string
:
assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");
#[must_use =
"this returns the replaced string as a new allocation, \
without modifying the original"]pub fn replace<'a, P>(&'a self, from: P, to: &str) -> String where
P: Pattern<'a>,
[src]
Replaces all matches of a pattern with another string.
replace
creates a new String
, and copies the data from this string slice into it. While doing so, it attempts to find matches of a pattern. If it finds any, it replaces them with the replacement string slice.
Basic usage:
let s = "this is old"; assert_eq!("this is new", s.replace("old", "new"));
When the pattern doesn't match:
let s = "this is old"; assert_eq!(s, s.replace("cookie monster", "little lamb"));
#[must_use =
"this returns the replaced string as a new allocation, \
without modifying the original"]pub fn replacen<'a, P>(&'a self, pat: P, to: &str, count: usize) -> String where
P: Pattern<'a>,
[src]1.16.0
Replaces first N matches of a pattern with another string.
replacen
creates a new String
, and copies the data from this string slice into it. While doing so, it attempts to find matches of a pattern. If it finds any, it replaces them with the replacement string slice at most count
times.
Basic usage:
let s = "foo foo 123 foo"; assert_eq!("new new 123 foo", s.replacen("foo", "new", 2)); assert_eq!("faa fao 123 foo", s.replacen('o', "a", 3)); assert_eq!("foo foo new23 foo", s.replacen(char::is_numeric, "new", 1));
When the pattern doesn't match:
let s = "this is old"; assert_eq!(s, s.replacen("cookie monster", "little lamb", 10));
pub fn to_lowercase(&self) -> String
[src]1.2.0
Returns the lowercase equivalent of this string slice, as a new String
.
'Lowercase' is defined according to the terms of the Unicode Derived Core Property Lowercase
.
Since some characters can expand into multiple characters when changing the case, this function returns a String
instead of modifying the parameter in-place.
Basic usage:
let s = "HELLO"; assert_eq!("hello", s.to_lowercase());
A tricky example, with sigma:
let sigma = "Σ"; assert_eq!("σ", sigma.to_lowercase()); // but at the end of a word, it's ς, not σ: let odysseus = "ὈΔΥΣΣΕΎΣ"; assert_eq!("ὀδυσσεύς", odysseus.to_lowercase());
Languages without case are not changed:
let new_year = "农历新年"; assert_eq!(new_year, new_year.to_lowercase());
pub fn to_uppercase(&self) -> String
[src]1.2.0
Returns the uppercase equivalent of this string slice, as a new String
.
'Uppercase' is defined according to the terms of the Unicode Derived Core Property Uppercase
.
Since some characters can expand into multiple characters when changing the case, this function returns a String
instead of modifying the parameter in-place.
Basic usage:
let s = "hello"; assert_eq!("HELLO", s.to_uppercase());
Scripts without case are not changed:
let new_year = "农历新年"; assert_eq!(new_year, new_year.to_uppercase());
One character can become multiple:
let s = "tschüß"; assert_eq!("TSCHÜSS", s.to_uppercase());
pub fn repeat(&self, n: usize) -> String
[src]1.16.0
Creates a new String
by repeating a string n
times.
This function will panic if the capacity would overflow.
Basic usage:
assert_eq!("abc".repeat(4), String::from("abcabcabcabc"));
A panic upon overflow:
// this will panic at runtime "0123456789abcdef".repeat(usize::MAX);
pub fn to_ascii_uppercase(&self) -> String
[src]1.23.0
Returns a copy of this string where each character is mapped to its ASCII upper case equivalent.
ASCII letters 'a' to 'z' are mapped to 'A' to 'Z', but non-ASCII letters are unchanged.
To uppercase the value in-place, use make_ascii_uppercase
.
To uppercase ASCII characters in addition to non-ASCII characters, use to_uppercase
.
let s = "Grüße, Jürgen ❤"; assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());
pub fn to_ascii_lowercase(&self) -> String
[src]1.23.0
Returns a copy of this string where each character is mapped to its ASCII lower case equivalent.
ASCII letters 'A' to 'Z' are mapped to 'a' to 'z', but non-ASCII letters are unchanged.
To lowercase the value in-place, use make_ascii_lowercase
.
To lowercase ASCII characters in addition to non-ASCII characters, use to_lowercase
.
let s = "Grüße, Jürgen ❤"; assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());
impl<'_> Add<&'_ str> for String
[src]
Implements the +
operator for concatenating two strings.
This consumes the String
on the left-hand side and re-uses its buffer (growing it if necessary). This is done to avoid allocating a new String
and copying the entire contents on every operation, which would lead to O(n^2) running time when building an n-byte string by repeated concatenation.
The string on the right-hand side is only borrowed; its contents are copied into the returned String
.
Concatenating two String
s takes the first by value and borrows the second:
let a = String::from("hello"); let b = String::from(" world"); let c = a + &b; // `a` is moved and can no longer be used here.
If you want to keep using the first String
, you can clone it and append to the clone instead:
let a = String::from("hello"); let b = String::from(" world"); let c = a.clone() + &b; // `a` is still valid here.
Concatenating &str
slices can be done by converting the first to a String
:
let a = "hello"; let b = " world"; let c = a.to_string() + b;
type Output = String
The resulting type after applying the +
operator.
fn add(self, other: &str) -> String
[src]
impl<'_> AddAssign<&'_ str> for String
[src]1.12.0
Implements the +=
operator for appending to a String
.
This has the same behavior as the push_str
method.
fn add_assign(&mut self, other: &str)
[src]
impl AsMut<str> for String
[src]1.43.0
impl AsRef<[u8]> for String
[src]
fn as_ref(&self) -> &[u8]ⓘNotable traits for &'_ [u8]
impl<'_> Read for &'_ [u8]
impl<'_> Write for &'_ mut [u8]
[src]
impl AsRef<OsStr> for String
[src]
impl AsRef<Path> for String
[src]
impl AsRef<str> for String
[src]
impl Borrow<str> for String
[src]
impl BorrowMut<str> for String
[src]1.36.0
fn borrow_mut(&mut self) -> &mut str
[src]
impl Clone for String
[src]
impl Debug for String
[src]
impl Default for String
[src]
impl Deref for String
[src]
impl DerefMut for String
[src]1.3.0
impl Display for String
[src]
impl Eq for String
[src]
impl<'a> Extend<&'a char> for String
[src]1.2.0
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = &'a char>,
[src]
fn extend_one(&mut self, &'a char)
[src]
fn extend_reserve(&mut self, additional: usize)
[src]
impl<'a> Extend<&'a str> for String
[src]
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = &'a str>,
[src]
fn extend_one(&mut self, s: &'a str)
[src]
fn extend_reserve(&mut self, additional: usize)
[src]
impl Extend<Box<str>> for String
[src]1.45.0
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = Box<str>>,
[src]
fn extend_one(&mut self, item: A)
[src]
fn extend_reserve(&mut self, additional: usize)
[src]
impl<'a> Extend<Cow<'a, str>> for String
[src]1.19.0
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = Cow<'a, str>>,
[src]
fn extend_one(&mut self, s: Cow<'a, str>)
[src]
fn extend_reserve(&mut self, additional: usize)
[src]
impl Extend<String> for String
[src]1.4.0
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = String>,
[src]
fn extend_one(&mut self, s: String)
[src]
fn extend_reserve(&mut self, additional: usize)
[src]
impl Extend<char> for String
[src]
fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = char>,
[src]
fn extend_one(&mut self, c: char)
[src]
fn extend_reserve(&mut self, additional: usize)
[src]
impl<'_> From<&'_ String> for String
[src]1.35.0
impl<'_> From<&'_ mut str> for String
[src]1.44.0
fn from(s: &mut str) -> String
[src]
Converts a &mut str
into a String
.
The result is allocated on the heap.
impl<'_> From<&'_ str> for String
[src]
impl<'a> From<&'a String> for Cow<'a, str>
[src]1.28.0
impl From<Box<str>> for String
[src]1.18.0
fn from(s: Box<str>) -> String
[src]
Converts the given boxed str
slice to a String
. It is notable that the str
slice is owned.
Basic usage:
let s1: String = String::from("hello world"); let s2: Box<str> = s1.into_boxed_str(); let s3: String = String::from(s2); assert_eq!("hello world", s3)
impl<'a> From<Cow<'a, str>> for String
[src]1.14.0
impl From<String> for Box<str>
[src]1.20.0
fn from(s: String) -> Box<str>ⓘNotable traits for Box<F>
impl<F> Future for Box<F> where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<I> Iterator for Box<I> where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized> Read for Box<R>
impl<W: Write + ?Sized> Write for Box<W>
[src]
Converts the given String
to a boxed str
slice that is owned.
Basic usage:
let s1: String = String::from("hello world"); let s2: Box<str> = Box::from(s1); let s3: String = String::from(s2); assert_eq!("hello world", s3)
impl From<String> for Vec<u8>
[src]1.14.0
fn from(string: String) -> Vec<u8>ⓘNotable traits for Vec<u8>
impl Write for Vec<u8>
[src]
Converts the given String
to a vector Vec
that holds values of type u8
.
Basic usage:
let s1 = String::from("hello world"); let v1 = Vec::from(s1); for b in v1 { println!("{}", b); }
impl From<String> for Arc<str>
[src]1.21.0
impl<'a> From<String> for Cow<'a, str>
[src]
impl From<String> for Rc<str>
[src]1.21.0
impl From<String> for Box<dyn Error + Send + Sync>
[src]
fn from(err: String) -> Box<dyn Error + Send + Sync>ⓘNotable traits for Box<F>
impl<F> Future for Box<F> where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<I> Iterator for Box<I> where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized> Read for Box<R>
impl<W: Write + ?Sized> Write for Box<W>
[src]
Converts a String
into a box of dyn Error
+ Send
+ Sync
.
use std::error::Error; use std::mem; let a_string_error = "a string error".to_string(); let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error); assert!( mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
impl From<String> for Box<dyn Error>
[src]1.6.0
fn from(str_err: String) -> Box<dyn Error>ⓘNotable traits for Box<F>
impl<F> Future for Box<F> where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<I> Iterator for Box<I> where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized> Read for Box<R>
impl<W: Write + ?Sized> Write for Box<W>
[src]
impl From<String> for OsString
[src]
impl From<String> for PathBuf
[src]
fn from(s: String) -> PathBuf
[src]
Converts a String
into a PathBuf
This conversion does not allocate or copy memory.
impl From<char> for String
[src]1.46.0
impl<'a> FromIterator<&'a char> for String
[src]1.17.0
fn from_iter<I>(iter: I) -> String where
I: IntoIterator<Item = &'a char>,
[src]
impl<'a> FromIterator<&'a str> for String
[src]
fn from_iter<I>(iter: I) -> String where
I: IntoIterator<Item = &'a str>,
[src]
impl FromIterator<Box<str>> for String
[src]1.45.0
impl<'a> FromIterator<Cow<'a, str>> for String
[src]1.19.0
impl<'a> FromIterator<String> for Cow<'a, str>
[src]1.12.0
impl FromIterator<String> for String
[src]1.4.0
fn from_iter<I>(iter: I) -> String where
I: IntoIterator<Item = String>,
[src]
impl FromIterator<char> for String
[src]
fn from_iter<I>(iter: I) -> String where
I: IntoIterator<Item = char>,
[src]
impl FromStr for String
[src]
type Err = Infallible
The associated error which can be returned from parsing.
fn from_str(s: &str) -> Result<String, <String as FromStr>::Err>
[src]
impl Hash for String
[src]
fn hash<H>(&self, hasher: &mut H) where
H: Hasher,
[src]
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
[src]1.3.0
impl Index<Range<usize>> for String
[src]
type Output = str
The returned type after indexing.
fn index(&self, index: Range<usize>) -> &str
[src]
impl Index<RangeFrom<usize>> for String
[src]
type Output = str
The returned type after indexing.
fn index(&self, index: RangeFrom<usize>) -> &str
[src]
impl Index<RangeFull> for String
[src]
impl Index<RangeInclusive<usize>> for String
[src]1.26.0
type Output = str
The returned type after indexing.
fn index(&self, index: RangeInclusive<usize>) -> &str
[src]
impl Index<RangeTo<usize>> for String
[src]
type Output = str
The returned type after indexing.
fn index(&self, index: RangeTo<usize>) -> &str
[src]
impl Index<RangeToInclusive<usize>> for String
[src]1.26.0
type Output = str
The returned type after indexing.
fn index(&self, index: RangeToInclusive<usize>) -> &str
[src]
impl IndexMut<Range<usize>> for String
[src]1.3.0
impl IndexMut<RangeFrom<usize>> for String
[src]1.3.0
impl IndexMut<RangeFull> for String
[src]1.3.0
impl IndexMut<RangeInclusive<usize>> for String
[src]1.26.0
fn index_mut(&mut self, index: RangeInclusive<usize>) -> &mut str
[src]
impl IndexMut<RangeTo<usize>> for String
[src]1.3.0
impl IndexMut<RangeToInclusive<usize>> for String
[src]1.26.0
fn index_mut(&mut self, index: RangeToInclusive<usize>) -> &mut str
[src]
impl Ord for String
[src]
fn cmp(&self, other: &String) -> Ordering
[src]
fn max(self, other: Self) -> Self
[src]1.21.0
fn min(self, other: Self) -> Self
[src]1.21.0
fn clamp(self, min: Self, max: Self) -> Self
[src]
impl<'a, 'b> PartialEq<&'a str> for String
[src]
impl<'a, 'b> PartialEq<Cow<'a, str>> for String
[src]
impl<'a, 'b> PartialEq<String> for str
[src]
impl PartialEq<String> for String
[src]
impl<'a, 'b> PartialEq<String> for &'a str
[src]
impl<'a, 'b> PartialEq<String> for Cow<'a, str>
[src]
impl<'a, 'b> PartialEq<str> for String
[src]
impl PartialOrd<String> for String
[src]
fn partial_cmp(&self, other: &String) -> Option<Ordering>
[src]
fn lt(&self, other: &String) -> bool
[src]
fn le(&self, other: &String) -> bool
[src]
fn gt(&self, other: &String) -> bool
[src]
fn ge(&self, other: &String) -> bool
[src]
impl<'a, 'b> Pattern<'a> for &'b String
[src]
A convenience impl that delegates to the impl for &str
.
assert_eq!(String::from("Hello world").find("world"), Some(6));
type Searcher = <&'b str as Pattern<'a>>::Searcher
Associated searcher for this pattern
fn into_searcher(self, haystack: &'a str) -> <&'b str as Pattern<'a>>::Searcher
[src]
fn is_contained_in(self, haystack: &'a str) -> bool
[src]
fn is_prefix_of(self, haystack: &'a str) -> bool
[src]
fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>
[src]
fn is_suffix_of(self, haystack: &'a str) -> bool
[src]
fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str>
[src]
impl StructuralEq for String
[src]
impl ToSocketAddrs for String
[src]1.16.0
type Iter = IntoIter<SocketAddr>
Returned iterator over socket addresses which this type may correspond to. Read more
fn to_socket_addrs(&self) -> Result<IntoIter<SocketAddr>>
[src]
impl ToString for String
[src]1.17.0
impl Write for String
[src]
impl RefUnwindSafe for String
impl Send for String
impl Sync for String
impl Unpin for String
impl UnwindSafe for String
impl<T> Any for T where
T: 'static + ?Sized,
[src]
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
fn borrow(&self) -> &TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized,
type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized,
type Item = <I as Iterator>::Item;
impl<R: Read + ?Sized, '_> Read for &'_ mut R
impl<W: Write + ?Sized, '_> Write for &'_ mut W
[src]
impl<T> From<T> for T
[src]
impl<T, U> Into<U> for T where
U: From<T>,
[src]
impl<T> ToOwned for T where
T: Clone,
[src]
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
[src]
fn clone_into(&self, target: &mut T)
[src]
impl<T> ToString for T where
T: Display + ?Sized,
[src]
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/string/struct.String.html