std::copy_n

From Cppreference

Copies exactly count values from the range beginning at first to the range beginning at result, if count>0. Does nothing otherwise.

[edit] Parameters

[edit] Return value

Iterator in the destination range, pointing past the last element copied if count>0 or first otherwise.

[edit] Complexity

Exactly count assignments, if count>0.

[edit] Equivalent function

template< class InputIterator, class Size, class OutputIterator>
OutputIterator copy_n(InputIterator first, Size count, OutputIterator result)
{
    if (count > 0) {
        *result++ = *first;
        for (Size i = 1; i < count; ++i) {
            *result++ = *++first;
        }
    }
    return result;
}

[edit] Example

#include <iostream>
#include <string>
#include <algorithm>
#include <iterator>
 
int main()
{
    std::string in = "1234567890";
    std::string out;
 
    std::copy_n(in.begin(), 4, std::back_inserter(out));
    std::cout << out << '\n';
}

Output:

1234

[edit] See also