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

NAME
       std::basic_string::starts_with -	std::basic_string::starts_with

Synopsis
	  constexpr bool starts_with( std::basic_string_view<CharT,Traits>
	  sv								     )
       (1) (since C++20)
	  const	noexcept;
	  constexpr   bool   starts_with(   CharT   c	)   const    noexcept;
       (2) (since C++20)
	  constexpr    bool    starts_with(    const   CharT*	s   )	const;
       (3) (since C++20)

	  Checks if the	string begins with the given prefix. The prefix	may be
       one of the
	  following:

	  1) a string view sv (which may be a result  of  implicit  conversion
       from another
	  std::basic_string).
	  2) a single character	c.
	  3) a null-terminated character string	s.

	  All three overloads effectively return std::basic_string_view<CharT,
       Traits>(data(),
	  size()).starts_with(x), where	x is the parameter.

Parameters
	  sv - a string	view which may be a result of implicit conversion from
       another
	       std::basic_string
	  c  - a single	character
	  s  - a null-terminated character string

Return value
	  true if the string begins with the provided prefix, false otherwise.

Notes
	  Feature-test macro: __cpp_lib_starts_ends_with

Example
       // Run this code

	#include <iostream>
	#include <string_view>
	#include <string>

	template <typename PrefixType>
	void test_prefix_print(const std::string& str, PrefixType prefix)
	{
	    std::cout  <<  '\''	<< str << "' starts with '" << prefix << "': "
       <<
		str.starts_with(prefix)	<< '\n';
	}

	int main()
	{
	    std::boolalpha(std::cout);
	    auto helloWorld = std::string("hello world");

	    test_prefix_print(helloWorld, std::string_view("hello"));

	    test_prefix_print(helloWorld, std::string_view("goodbye"));

	    test_prefix_print(helloWorld, 'h');

	    test_prefix_print(helloWorld, 'x');
	}

Output:
	'hello world' starts with 'hello': true
	'hello world' starts with 'goodbye': false
	'hello world' starts with 'h': true
	'hello world' starts with 'x': false

See also
	  ends_with   checks if	the string ends	with the given suffix
	  (C++20)     (public member function)
	  starts_with checks if	the string view	starts with the	given prefix
	  (C++20)	  (public     member	 function     of      std::ba-
       sic_string_view<CharT,Traits>)
	  ends_with   checks if	the string view	ends with the given suffix
	  (C++20)	   (public     member	  function     of     std::ba-
       sic_string_view<CharT,Traits>)
	  contains    checks if	the string contains  the  given	 substring  or
       character
	  (C++23)     (public member function)
	  contains     checks  if the string view contains the given substring
       or character
	  (C++23)	  (public     member	 function     of      std::ba-
       sic_string_view<CharT,Traits>)
	  compare     compares two strings
		      (public member function)
	  substr      returns a	substring
		      (public member function)

http://cppreference.com		  2022.07.31	  std::basic_...starts_with(3)

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