std::basic_string::find_last_not_of(3)

NAME
std::basic_string::find_last_not_of - std::basic_string::find_last_not_of

Synopsis
   size_type find_last_not_of( const (until
   basic_string& str, C++11)
   size_type pos = npos ) const;
   size_type find_last_not_of( const (since
   basic_string& str, C++11)
   size_type pos = npos ) const (until
   noexcept; C++20)
   constexpr size_type
   find_last_not_of( const (since
   basic_string& str, C++20)
   size_type pos = npos ) const
   noexcept;
   size_type find_last_not_of( const
   CharT* s, (until
   size_type pos, size_type count ) C++20)
   const;
   constexpr size_type
   find_last_not_of( const CharT* s, (since
   size_type pos, size_type count ) C++20)
   const;
   size_type find_last_not_of( const (until
   CharT* s, size_type pos = npos ) C++20)
   const;
   constexpr size_type (since
   find_last_not_of( const CharT* s, C++20)
   size_type pos = npos ) const; (1)
   size_type find_last_not_of( CharT (until
   ch, size_type pos = npos ) const; C++11)
   size_type find_last_not_of( CharT (since
   ch, size_type pos = npos ) const C++11)
   noexcept; (until
                        (2) C++20)
   constexpr size_type
   find_last_not_of( CharT ch, (since
   size_type pos = npos ) const C++20)
   noexcept; (3)
   template < class StringViewLike >
   size_type (4) (since
   find_last_not_of( const C++17)
   StringViewLike& t, (until
                        C++20)
   size_type pos = npos ) const
   noexcept(/* see below */); (5)
   template < class StringViewLike >
   constexpr size_type
   find_last_not_of( const (since
   StringViewLike& t, C++20)
   size_type pos = npos ) const
   noexcept(/* see below */);
   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
// Run this code
 #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 avoided by making it a
                       some cases template
   P1148R0 C++11 noexcept for overload (4)/(5) was restored
            C++17 accidently dropped by LWG2064/LWG2946

See also
   find find characters in the string
                     (public member function)
   rfind find the last occurrence of a substring
                     (public member function)
   find_first_of find first occurrence of characters
                     (public member function)
   find_first_not_of find first absence of characters
                     (public member function)
   find_last_of find last occurrence of characters
                     (public member function)
   find_last_not_of find last absence of characters
   (C++17) (public member function of std::basic_string_view<CharT,Traits>)