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std::basic_...ind_first_of(3)  C++ Standard Libary std::basic_...ind_first_of(3)

NAME
     std::basic_string_view::find_first_of		 -		std::ba-
     sic_string_view::find_first_of

Synopsis
	constexpr size_type
	    find_first_of( basic_string_view v, size_type pos = 0 )  const   (1)
     (since C++17)
	noexcept;
	constexpr  size_type						     (2)
     (since C++17)
	    find_first_of( CharT ch, size_type pos = 0 ) const noexcept;
	constexpr size_type
	    find_first_of( const CharT* s, size_type pos, size_type  count   (3)
     (since C++17)
	) const;
	constexpr  size_type						     (4)
     (since C++17)
	    find_first_of( const CharT* s, size_type pos = 0 ) const;

	Finds the first character equal to any of the characters  in  the  given
     character
	sequence.

	1)  Finds  the	first  occurrence  of any of the characters of v in this
     view, starting
	at position pos.
	2) Equivalent to find_first_of(basic_string_view(std::addressof(ch), 1),
     pos).
	3) Equivalent to find_first_of(basic_string_view(s, count), pos).
	4) Equivalent to find_first_of(basic_string_view(s), pos).

Parameters
	v     - view to search for
	pos   - position at which to start the search
	count - length of the string of characters to search for
	s     - pointer to a string of characters to search for
	ch    - character to search for

Return value
	Position of the first occurrence of any character of the  substring,  or
     npos if no
	such character is found.

Complexity
	O(size() * v.size()) at worst.

Example
     // Run this code

      #include <string_view>

      using namespace std::literals;
      constexpr auto N = std::string_view::npos;

      constexpr bool is_white_space(const char c)
      {
	  return " \t\n\f\r\v"sv.find_first_of(c) != N;
      };

      static_assert(
	  1 == "alignas"sv.find_first_of("klmn"sv) &&
	    //	 aaaaaaaaaaaaaaaaaaaaaaaaaaa
	  N == "alignof"sv.find_first_of("wxyz"sv) &&
	    //
	  3 == "concept"sv.find_first_of("bcde"sv, /* pos= */ 1) &&
	    //	   aaaaaaaaaaaaaaaaaaaaaaaaa
	  N == "consteval"sv.find_first_of("oxyz"sv, /* pos= */ 2) &&
	    //
	  6 == "constexpr"sv.find_first_of('x') &&
	    //	      aaaaaaaaaaaaaaaaaaaaaaa
	  N == "constinit"sv.find_first_of('x') &&
	    //
	  6 == "const_cast"sv.find_first_of('c', /* pos= */ 4) &&
	    //	      aaaaaaaaaaaaaaaaaaaaaaaa
	  N == "continue"sv.find_first_of('c', /* pos= */ 42) &&
	    //
	  5 == "co_await"sv.find_first_of("cba", /* pos= */ 4) &&
	    //	     aaaaaaaaaaaaaaaaaaaaaaaaa
	  7  ==  "decltype"sv.find_first_of("def", /* pos= */ 2, /* count= */ 2)
     &&
	    //	       aaaaaaaaaaaaaaaaaaaaaa
	  N == "decltype"sv.find_first_of("def", /* pos= */ 2, /* count=  */  1)
     &&
	    //
	  is_white_space(' ') && is_white_space('\r') && !is_white_space('\a')
      );

      int main() {}

See also
	find		  find characters in the view
			  (public member function)
	rfind		  find the last occurrence of a substring
			  (public member function)
	find_last_of	  find last occurrence of characters
			  (public member function)
	find_first_not_of find first absence of characters
			  (public member function)
	find_last_not_of  find last absence of characters
			  (public member function)
			  find first occurrence of characters
	find_first_of	  (public member function of
			  std::basic_string<CharT,Traits,Allocator>)

http://cppreference.com 	   2024.06.10	   std::basic_...ind_first_of(3)
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