std::generate_n

From Cppreference

Assigns values, generated by given function object g, to the first count elements in the range beginning at first, if count>0. Does nothing otherwise.

[edit] Parameters

[edit] Return value

(none) (pre-C++11 version)

Iterator one past the last element assigned if count>0, first otherwise. (C++11 version)

[edit] Complexity

Exactly count invocations of g() and assignments, for count>0.

[edit] Equivalent function

template< class OutputIterator, class Size, class Generator >
void generate_n( OutputIterator first, Size count, Generator g )
{
    for( Size i = 0; i < count; i++ ) {
        *first++ = g();
    }
    return first;
}

[edit] Example

The following code fills an array of integers with random numbers.

#include <cstddef>
#include <cstdlib>
#include <iostream>
#include <iterator>
#include <algorithm>
 
int main()
{
    const std::size_t N = 5;
    int ar[N];
    std::generate_n(ar, N, std::rand); // Using the C function rand()
 
    std::cout << "ar: ";
    std::copy(ar, ar+N, std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
}

Output:

52894 15984720 41513563 41346135 51451456

[edit] See also