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std::basic_string::copy(3)     C++ Standard Libary    std::basic_string::copy(3)

NAME
     std::basic_string::copy - std::basic_string::copy

Synopsis
	size_type  copy( CharT* dest, size_type count, size_type pos  (constexpr
     since C++20)
	= 0 ) const;

	Copies a substring [pos, pos + count) to character string pointed to  by
     dest. If the
	requested  substring  lasts  past  the end of the string, or if count ==
     npos, the
	copied substring is [pos, size()).

	The resulting character string is not null-terminated.

Parameters
	dest  - pointer to the destination character string
	count - length of the substring
	pos   - position of the first character to include

Return value
	Number of characters copied.

Exceptions
	std::out_of_range if pos > size().

	If an exception is thrown for any reason, this function  has  no  effect
     (strong
	exception safety guarantee).

Complexity
	Linear in count.

Example
     // Run this code

      #include <iostream>
      #include <string>

      int main()
      {
	  std::string foo("WINE");

	  // brace-initialization initializes all characters to 0,
	  // providing a null-terminator
	  char bar[4]{};

	  // do not copy the last char, to guarantee null-termination
	  foo.copy(bar, sizeof bar - 1);

	  std::cout << bar << '\n'; // requires bar to be null-terminated
      }

Output:
      WIN

	Defect reports

	The  following	behavior-changing  defect  reports were applied retroac-
     tively to
	previously published C++ standards.

	  DR	Applied to	  Behavior as published 	     Correct be-
     havior
	LWG 847 C++98	   there was no exception safety       added strong  ex-
     ception safety
			   guarantee			       guarantee

See also
	substr	returns a substring
		(public member function)
	copy	copies characters
		(public member function of std::basic_string_view<CharT,Traits>)
	copy	copies a range of elements to a new location
	copy_if (function template)
	(C++11)
	memcpy	copies one buffer to another
		(function)

http://cppreference.com 	   2024.06.10	      std::basic_string::copy(3)
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