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std::basic_..._view::copy(3)  C++ Standard Libary std::basic_..._view::copy(3)

NAME
       std::basic_string_view::copy - std::basic_string_view::copy

Synopsis
	  size_type  copy(  CharT*  dest, size_type count, size_type pos = 0 )
       (since C++17)
	  const;
       (until C++20)
	  constexpr   size_type	  copy(	  CharT*   dest,   size_type	count,
       (since C++20)
	  size_type pos	= 0 ) const;

	  Copies  the  substring  [pos,	 pos  +	rcount)	to the character array
       pointed to by dest,
	  where	rcount is the smaller of count and size() - pos.

	  Equivalent to	Traits::copy(dest, data() + pos, rcount).

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

Return value
	  Number of characters copied

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

Complexity
	  Linear in rcount.

Example
       // Run this code

	#include <array>
	#include <cstddef>
	#include <iostream>
	#include <stdexcept>
	#include <string_view>

	int main()
	{
	    constexpr std::basic_string_view<char> source{"ABCDEF"};
	    std::array<char, 8>	dest;
	    std::size_t	count{}, pos{};

	    dest.fill('\0');
	    source.copy(dest.data(), count = 4); // pos	= 0
	    std::cout << dest.data() <<	'\n'; // ABCD

	    dest.fill('\0');
	    source.copy(dest.data(), count = 4,	pos = 1);
	    std::cout << dest.data() <<	'\n'; // BCDE

	    dest.fill('\0');
	    source.copy(dest.data(), count = 42, pos = 2); // ok, count	-> 4
	    std::cout << dest.data() <<	'\n'; // CDEF

	    try
	    {
		source.copy(dest.data(), count = 1, pos	= 666);	// throws: pos
       > size()
	    }
	    catch(std::out_of_range const& ex)
	    {
		std::cout << ex.what() << '\n';
	    }
	}

Output:
	ABCD
	BCDE
	CDEF
	basic_string_view::copy: __pos (which is 666) >	__size (which is 6)

See also
	  substr  returns a substring
	  (C++17) (public member function)
	  copy	  copies characters
		  (public	member	     function	    of	      std::ba-
       sic_string<CharT,Traits,Allocator>)
	  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		  2022.07.31	  std::basic_..._view::copy(3)

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