std::string copy() method

since C++20

// Const version only
constexpr size_type copy( CharT* dest, size_type count, size_type pos = 0 ) const;

until C++20

// Const version only
size_type copy( CharT* dest, size_type count, size_type pos = 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.

Complexity

Linear in count - O(count).

Exceptions

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

Example

#include <string>
#include <iostream>
 
int main()
{
  std::string foo("quuuux");
  char bar[7]{};
  foo.copy(bar, sizeof bar);
  std::cout << bar << '\n';
}

Output

quuuux