std::basic_string<CharT,Traits,Allocator>::find_last_not_of
(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 interval [0, pos]. If the character is not present in the interval, npos
will be returned.
1) Finds the last character equal to none of characters in
str
.
2) Finds the last character equal to none of characters in the range
[s, s+count)
. This range can include null characters.
3) Finds the last character equal to none of characters in character string pointed to by
s
. The length of the string is determined by the first null character using
Traits::length(s)
.
4) Finds the last character not equal to
ch
.
5) Implicitly converts
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
. This overload participates in overload resolution only if
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
.
Parameters
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 |
Return value
Position of the found character or npos
if no such character is found.
Exceptions
5)
noexcept
specification:
noexcept(std::is_nothrow_convertible_v<const T&, std::basic_string_view<charT, traits>>)
Example
#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
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2064 | C++11 | overload (3) and (4) were noexcept | removed |
LWG 2946 | C++17 | string_view overload causes ambiguity in some cases |
avoided by making it a template |
P1148R0 | C++11 C++17 |
noexcept for overload (4)/(5) was accidently dropped by LWG2064/LWG2946 | restored |
See also
find characters in the string (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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