constexpr basic_string_view() noexcept; | (1) | (since C++17) |
constexpr basic_string_view( const basic_string_view& other ) noexcept = default; | (2) | (since C++17) |
constexpr basic_string_view( const CharT* s, size_type count ); | (3) | (since C++17) |
constexpr basic_string_view( const CharT* s ); | (4) | (since C++17) |
template< class It, class End > constexpr basic_string_view( It first, End last ); | (5) | (since C++20) |
template< class R > constexpr explicit basic_string_view( R&& r ); | (6) | (since C++23) |
constexpr basic_string_view( std::nullptr_t ) = delete; | (7) | (since C++23) |
std::basic_string_view
. After construction, data()
is equal to nullptr
, and size()
is equal to 0
.other
. After construction, data()
is equal to other.data()
, and size()
is equal to other.size()
.count
characters of the character array starting with the element pointed by s
. s
can contain null characters. The behavior is undefined if [
s
,
s + count
)
is not a valid range (even though the constructor may not access any of the elements of this range). After construction, data()
is equal to s
, and size()
is equal to count
.s
, not including the terminating null character. The length of the view is determined as if by Traits::length(s)
. The behavior is undefined if [
s
,
s + Traits::length(s)
)
is not a valid range. After construction, data()
is equal to s
, and size()
is equal to Traits::length(s)
.std::basic_string_view
over the range [
first
,
last
)
. The behavior is undefined if [
first
,
last
)
is not a valid range, if It
does not actually model contiguous_iterator
, or if End
does not actually model sized_sentinel_for
for It
. After construction, data()
is equal to std::to_address(first)
, and size()
is equal to last - first
. This overload participates in overload resolution only if.
It
satisfies contiguous_iterator
, End
satisfies sized_sentinel_for
for It
, CharT
are the same type, and End
is not convertible to std::size_t
.std::basic_string_view
over the range r
. After construction, data()
is equal to ranges::data(r)
, and size()
is equal to ranges::size(r)
. This overload participates in overload resolution only if.
std::basic_string_view
, R
models contiguous_range
and sized_range
, CharT
are the same type, R
is not convertible to const CharT*, and d
be an lvalue of type std::remove_cvref_t<R>, d.operator ::std::basic_string_view<CharT, Traits>()
is not a valid expression.std::basic_string_view
cannot be constructed from nullptr
.other | - | another view to initialize the view with |
s | - | pointer to a character array or a C string to initialize the view with |
count | - | number of characters to include in the view |
first | - | iterator to the first character of the sequence |
last | - | iterator past the last character of the sequence or another sentinel |
r | - | a contiguous range that contains the sequence |
s
.#include <array> #include <iomanip> #include <iostream> #include <string> #include <string_view> int main() { std::string cppstr = "Foo"; std::string_view cppstr_v(cppstr); // overload (2), after // std::string::operator string_view std::cout << "1) cppstr_v: " << std::quoted(cppstr_v) << '\n'; char array[3] = {'B', 'a', 'r'}; std::string_view array_v(array, std::size(array)); // overload (3) std::cout << "2) array_v: " << std::quoted(array_v) << '\n'; const char* one_0_two = "One\0Two"; std::string_view one_two_v{one_0_two, 7}; // overload (3) std::cout << "3) one_two_v: \""; for (char c : one_two_v) std::cout << (c != '\0' ? c : '?'); std::cout << "\", one_two_v.size(): " << one_two_v.size() << '\n'; std::string_view one_v{one_0_two}; // overload (4) std::cout << "4) one_v: " << std::quoted(one_v) << ", one_v.size(): " << one_v.size() << '\n'; constexpr std::wstring_view wcstr_v = L"xyzzy"; // overload (4) std::cout << "5) wcstr_v.size(): " << wcstr_v.size() << '\n'; std::array ar = {'P', 'u', 'b'}; std::string_view ar_v(ar.begin(), ar.end()); // overload (5), C++20 std::cout << "6) ar_v: " << std::quoted(ar_v) << '\n'; // std::string_view ar_v2{ar}; // overload (6), OK in C++23 // std::cout << "ar_v2: " << std::quoted(ar_v2) << '\n'; // ar_v2: "Pub" [[maybe_unused]] auto zero = [] { /* ... */ return nullptr; }; // std::string_view s{zero()}; // overload (7), won't compile since C++23 }
Output:
1) cppstr_v: "Foo" 2) array_v: "Bar" 3) one_two_v: "One?Two", one_two_v.size(): 7 4) one_v: "One", one_v.size(): 3 5) wcstr_v.size(): 5 6) ar_v: "Pub"
(C++17) | assigns a view (public member function) |
constructs a basic_string (public member function of std::basic_string<CharT,Traits,Allocator> ) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/string/basic_string_view/basic_string_view