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std::basic_...ind_first_of(3) C++ Standard Libarystd::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) &&
	      //
	    N == "alignof"sv.find_first_of("wxyz"sv) &&
	      //
	    3 == "concept"sv.find_first_of("bcde"sv, /*	pos= */	1) &&
	      //
	    N == "consteval"sv.find_first_of("oxyz"sv, /* pos= */ 2) &&
	      //
	    6 == "constexpr"sv.find_first_of('x') &&
	      //
	    N == "constinit"sv.find_first_of('x') &&
	      //
	    6 == "const_cast"sv.find_first_of('c', /* pos= */ 4) &&
	      //
	    N == "continue"sv.find_first_of('c', /* pos= */ 42)	&&
	      //
	    5 == "co_await"sv.find_first_of("cba", /* pos= */ 4) &&
	      //
	    7  == "decltype"sv.find_first_of("def", /* pos= */ 2, /* count= */
       2) &&
	      //
	    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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