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copy_n

Copies a specified number of elements

Definition

The copy_n() algorithm is defined in the standard header <algorithm> and in the nonstandard backward-compatibility header <algo.h>.

Interface

#include <algorithm>
template < class InputIterator, class Size, class OutputIterator >
    OutputIterator copy_n(
        InputIterator  first, 
        Size count,
        OutputIterator result
     );

Parameters:
Parameter Description
first An input iterator that indicates where to copy elements from
count A signed or unsigned integer type specifying the number of elements to copy
result An output iterator that indicates where to copy elements to

Description

Copy_n copies elements from the range [first, first + n) to the range [result, result + n).

Return Value

Returns an output iterator where elements have been copied to. It is the same as the returned value of the third parameter, result.

Complexity

The complexity is linear, n assignments are performed.
Example:

Example - copy_n algorithm
Problem
This example of program illustrates the functionality of copy_n() algorithm.
Workings
#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';
 
    return 0;
}
Solution
Output:

1234
References