std::basic_string<CharT,Traits,Allocator>::find_first_not_of

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.

# Declarations

size_type find_first_not_of( const basic_string& str,
size_type pos = 0 ) const;

(noexcept since C++11) (constexpr since C++20)

size_type find_first_not_of( const CharT* s,
size_type pos, size_type count ) const;

(constexpr since C++20)

size_type find_first_not_of( const CharT* s,
size_type pos = 0 ) const;

(constexpr since C++20)

size_type find_first_not_of( CharT ch, size_type pos = 0 ) const;

(noexcept since C++11) (constexpr since C++20)

template< class StringViewLike >
size_type
find_first_not_of( const StringViewLike& t,
size_type pos = 0 ) const noexcept(/* see below */);

(since C++17) (constexpr since C++20)

# 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

# Return value

Position of the found character or std::string::npos if no such character is found.

# Example

#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';
}

# Defect reports

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++11C++17	noexcept for overloads (4,5) wereaccidentally dropped by LWG2064/LWG2946	restored