std::basic_string<CharT,Traits,Allocator>::find_first_not_of
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(DR*)
basic_string::find_first_not_of
(C++23)
(DR*)
(C++23)
(C++23)
(C++20)
(C++20)
(C++23)
(C++20)(C++20)
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
(C++11)(C++11)(C++11)
(C++11)(C++11)
(C++14)
(C++11)
size_type find_first_not_of( const basic_string& str,
size_type pos = 0 ) const;
(1)
(noexcept since C++11) size_type pos = 0 ) const;
(constexpr since C++20)
size_type find_first_not_of( const CharT* s,
size_type pos, size_type count ) const;
(2)
(constexpr since C++20)
size_type pos, size_type count ) const;
size_type find_first_not_of( const CharT* s,
size_type pos = 0 ) const;
(3)
(constexpr since C++20)
size_type pos = 0 ) const;
size_type find_first_not_of( CharT ch, size_type pos = 0 ) const;
(4)
(noexcept since C++11) (constexpr since C++20)
template< class StringViewLike >
(5)
(since C++17) size_type
find_first_not_of( const StringViewLike& t,
(constexpr since C++20)
Finds the first character equal to none of the characters in the given character sequence. The search considers only the range [pos, size() ). If all characters in the range can be found in the given character sequence, npos will be returned.
1) Finds the first character equal to none of characters in str.
2) Finds the first character equal to none of characters in range
[s, s + count). This range can include null characters. If
[s, s + count) is not a valid range, the behavior is undefined.3) Finds the first 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). If
[s, s + Traits::length(s)) is not a valid range, the behavior is undefined.4) Finds the first 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 first 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.
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.
[edit] Parameters
str
-
string identifying characters to search for
pos
-
position for the search to start from
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
[edit] Return value
Position of the found character or std::string::npos if no such character is found.
[edit] Exceptions
1,4) Throws nothing.
5)
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).
[edit] Example
Run this code
#include <iostream> #include <string> int main() { // Permit uppercase letters, lowercase letters and numbers in macro names const char* pattern = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz" "0123456789"; std::string data = "1) %FIX, 2) %HACK, and 3) %TODO"; const std::string replacement = "%DONE%"; std::cout << "Before: " << data << '\n'; for (std::string::size_type first{}, last{}; (first = data.find('%', first)) != std::string::npos ; first += replacement.size()) { last = data.find_first_not_of(pattern, first + 1); if (last == std::string::npos ) last = data.length(); // Now first at '%' and last is one past end of the found substring data.replace(first, last - first, replacement); } std::cout << "After: " << data << '\n'; }
Output:
Before: 1) %FIX, 2) %HACK, and 3) %TODO After: 1) %DONE%, 2) %DONE%, and 3) %DONE%
[edit] 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 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 accidentally dropped by LWG2064/LWG2946 |
restored |
[edit] See also
find first absence of characters
(public member function of
(public member function of
std::basic_string_view<CharT,Traits>) [edit]