public member function
<string>
size_type copy (charT* s, size_type len, size_type pos = 0) const;
Copy sequence of characters from string
Copies a substring of the current value of the basic_string object into the array pointed by s. This substring contains the len characters that start at position pos.
The function does not append a null character at the end of the copied content.
Parameters
- s
- Pointer to an array of characters.
The array shall contain enough storage for the copied characters.
- len
- Number of characters to copy (if the string is shorter, as many characters as possible are copied).
- pos
- Position of the first character to be copied.
If this is greater than the string length, it throws out_of_range.
Note: The first character in the basic_string is denoted by a value of 0 (not 1).
Return value
The number of characters copied to the array pointed by s. This may be equal to len or to length()-pos (if the string value is shorter than pos+len).
Member type size_type is an unsigned integral type.
Example
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// string::copy
#include <iostream>
#include <string>
int main ()
{
char buffer[20];
std::string str ("Test string...");
std::size_t length = str.copy(buffer,6,5);
buffer[length]='\0';
std::cout << "buffer contains: " << buffer << '\n';
return 0;
}
| |
Output:
Complexity
Linear in the number of characters copied.
Iterator validity
No changes.
Data races
The object is accessed.
Exception safety
Strong guarantee: if an exception is thrown, there are no changes in the basic_string.
If s does not point to an array long enough, it causes undefined behavior.
If pos is greater than the string length, an out_of_range exception is thrown.