(1) | ||
size_type find_last_not_of( const basic_string& str, size_type pos = npos ) const; | (until C++11) | |
size_type find_last_not_of( const basic_string& str, size_type pos = npos ) const noexcept; | (since C++11) (until C++20) | |
constexpr size_type find_last_not_of( const basic_string& str, size_type pos = npos ) const noexcept; | (since C++20) | |
(2) | ||
size_type find_last_not_of( const CharT* s, size_type pos, size_type count ) const; | (until C++20) | |
constexpr size_type find_last_not_of( const CharT* s, size_type pos, size_type count ) const; | (since C++20) | |
(3) | ||
size_type find_last_not_of( const CharT* s, size_type pos = npos ) const; | (until C++20) | |
constexpr size_type find_last_not_of( const CharT* s, size_type pos = npos ) const; | (since C++20) | |
(4) | ||
size_type find_last_not_of( CharT ch, size_type pos = npos ) const; | (until C++11) | |
size_type find_last_not_of( CharT ch, size_type pos = npos ) const noexcept; | (since C++11) (until C++20) | |
constexpr size_type find_last_not_of( CharT ch, size_type pos = npos ) const noexcept; | (since C++20) | |
(5) | ||
template< class StringViewLike > size_type find_last_not_of( const StringViewLike& t, size_type pos = npos ) const noexcept(/* see below */); | (since C++17) (until C++20) | |
template< class StringViewLike > constexpr size_type find_last_not_of( const StringViewLike& t, size_type pos = npos ) const noexcept(/* see below */); | (since C++20) |
Finds the last character equal to none of the characters in the given character sequence. The search considers only the range [
0
,
pos
]
. If all characters in the range can be found in the given character sequence, npos
will be returned.
str
. [
s
,
s + count
)
. This range can include null characters.s
. The length of the string is determined by the first null character using Traits::length(s)
.ch
.t
to a string view sv
as if by std::basic_string_view<CharT, Traits> sv = t;
, then finds the last character equal to none of characters in sv
.std::is_convertible_v<const StringViewLike&,
std::basic_string_view<CharT, Traits>>
is true
and std::is_convertible_v<const StringViewLike&, const CharT*>
is false
.In all cases, equality is checked by calling Traits::eq
.
str | - | string identifying characters to search for |
pos | - | position at which to begin searching |
count | - | length of character string identifying characters to search for |
s | - | pointer to a character string identifying characters to search for |
ch | - | character identifying characters to search for |
t | - | object (convertible to std::basic_string_view ) identifying characters to search for |
Position of the found character or npos
if no such character is found.
noexcept
specification: noexcept(std::is_nothrow_convertible_v<
const T&, std::basic_string_view<CharT, Traits>>)
If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).
#include <iostream> #include <string> void show_pos(const std::string& str, std::string::size_type found) { if (found != std::string::npos) std::cout << '[' << found << "] = \'" << str[found] << "\'\n"; else std::cout << "not found\n"; } int main() { std::string str{"abc_123"}; char const* skip_set{"0123456789"}; std::string::size_type str_last_pos{std::string::npos}; show_pos(str, str.find_last_not_of(skip_set)); // [3] = '_' str_last_pos = 2; show_pos(str, str.find_last_not_of(skip_set, str_last_pos)); // [2] = 'c' str_last_pos = 2; show_pos(str, str.find_last_not_of('c', str_last_pos)); // [1] = 'b' const char arr[]{'3', '4', '5'}; show_pos(str, str.find_last_not_of(arr)); // [5] = '2' str_last_pos = 2; std::string::size_type skip_set_size{4}; show_pos(str, str.find_last_not_of(skip_set, str_last_pos, skip_set_size)); // [2] = 'c' show_pos(str, str.find_last_not_of("abc")); // [6] = '3' str_last_pos = 2; show_pos(str, str.find_last_not_of("abc", str_last_pos)); // not found }
Output:
[3] = '_' [2] = 'c' [1] = 'b' [5] = '2' [2] = 'c' [6] = '3' not found
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 141 | C++98 | overload (1) could only return npos if pos >= size() | the search range is[ 0 , size() ) in this case |
LWG 847 | C++98 | there was no exception safety guarantee | added strong exception safety guarantee |
LWG 2064 | C++11 | overloads (3,4) were noexcept | removed |
LWG 2946 | C++17 | overload (5) caused ambiguity in some cases | avoided by making it a template |
P1148R0 | C++11 C++17 | noexcept for overloads (4,5) were accidently dropped by LWG2064/LWG2946 | restored |
finds the first occurrence of the given substring (public member function) |
|
find the last occurrence of a substring (public member function) |
|
find first occurrence of characters (public member function) |
|
find first absence of characters (public member function) |
|
find last occurrence of characters (public member function) |
|
(C++17) | find last absence of characters (public member function of std::basic_string_view<CharT,Traits> ) |
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