Standard C++ Library Class Reference

Unless result is an insert iterator, copy assumes that at least as many elements follow result as are in

the range [first, last).

The copy_backward algorithm copies elements in the range specified by [first, last) into the range

specified by [result - (last - first), result), starting from the end of the sequence (last-1) and progressing

to the front (first). Note that copy_backward does not reverse the order of the elements, it simply

reverses the order of transfer. copy_backward returns result - (last - first). You should use

copy_backward instead of copy when last is in the range [result - (last - first), result). For each positive

integer n <= (last - first), copy_backward assigns *(last - n) to *(result - n). The result of

copy_backward is undefined if result is in the range [first, last).

Unless result is an insert iterator, copy_backward assumes that there are at least as many elements

ahead of result as are in the range [first, last).

Complexity

Both copy and copy_backward perform exactly last - first assignments.

Example

// stdlib/examples/manual.copyex.cpp

#include <algorithm>

#include <vector>

#include <iostream.h>

int main()

{

int d1[4] = {1,2,3,4};

int d2[4] = {5,6,7,8};

// Set up three vectors

vector<int> v1(d1,d1 + 4), v2(d2,d2 + 4), v3(d2,d2 + 4);

// Set up one empty vector

vector<int> v4;

// Copy v1 to v2

copy(v1.begin(),v1.end(),v2.begin());

// Copy backwards v1 to v3

copy_backward(v1.begin(),v1.end(),v3.end());

// Use insert iterator to copy into empty vector