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size_type find_first_not_of(const basic_string& str, size_type pos=0)const; | (1) | (noexcept since C++11) (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 find_first_not_of(const CharT* s, size_type pos=0)const; | (3) | (constexpr since C++20) |
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> size_type | (5) | (since C++17) (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.
[s, s+ count). This range can include null characters.[s, s+ count) is not avalid range, the behavior is undefined.Traits::length(s).[s, s+ Traits::length(s)) is not avalid range, the behavior is undefined.In all cases, equality is checked by callingTraits::eq.
Contents |
| 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 tostd::basic_string_view) identifying characters to search for |
Position of the found character orstd::string::npos if no such character is found.
If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).
#include <iostream>#include <string> int main(){// Permit uppercase letters, lowercase letters and numbers in macro namesconstchar* pattern="ABCDEFGHIJKLMNOPQRSTUVWXYZ""abcdefghijklmnopqrstuvwxyz""0123456789"; std::string data="1) %FIX, 2) %HACK, and 3) %TODO";conststd::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) %TODOAfter: 1) %DONE%, 2) %DONE%, and 3) %DONE%
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 |
| finds the first occurrence of the given substring (public member function)[edit] | |
| find the last occurrence of a substring (public member function)[edit] | |
| find first occurrence of characters (public member function)[edit] | |
| find last occurrence of characters (public member function)[edit] | |
| find last absence of characters (public member function)[edit] | |
| find first absence of characters (public member function of std::basic_string_view<CharT,Traits>)[edit] |
