fill_n
Assigns a new value to a specified number of elements in a range beginning with a particular element.
template<class OutputIterator, class Size, class Type>
OutputIterator fill_n(
OutputIterator First,
Size Count,
const Type& Val
);
Parameters
First
An output iterator addressing the position of the first element in the range to be assigned the value Val.Count
A signed or unsigned integer type specifying the number of elements to be assigned the value.Val
The value to be assigned to elements in the range [First, First + Count).
Return Value
An iterator to the element that follows the last element filled if Count > zero, otherwise the first element.
Remarks
The destination range must be valid; all pointers must be dereferenceable, and the last position is reachable from the first by incrementation. The complexity is linear with the size of the range.
fill_n has two related forms:
For information on how these functions behave, see Checked Iterators.
Example
// alg_fill_n.cpp
// compile using /EHsc
#include <vector>
#include <algorithm>
#include <iostream>
int main()
{
using namespace std;
vector <int> v;
for ( auto i = 0 ; i < 9 ; ++i )
v.push_back( 0 );
cout << " vector v = ( " ;
for ( const auto &w : v )
cout << w << " ";
cout << ")" << endl;
// Fill the first 3 positions with a value of 1, saving position.
auto pos = fill_n( v.begin(), 3, 1 );
cout << "modified v = ( " ;
for ( const auto &w : v )
cout << w << " ";
cout << ")" << endl;
// Fill the next 3 positions with a value of 2, using last position.
fill_n( pos, 3, 2 );
cout << "modified v = ( " ;
for ( const auto &w : v )
cout << w << " ";
cout << ")" << endl;
// Fill the last 3 positions with a value of 3, using relative math.
fill_n( v.end()-3, 3, 3 );
cout << "modified v = ( " ;
for ( const auto &w : v )
cout << w << " ";
cout << ")" << endl;
}
Output
vector v = ( 0 0 0 0 0 0 0 0 0 )
modified v = ( 1 1 1 0 0 0 0 0 0 )
modified v = ( 1 1 1 2 2 2 0 0 0 )
modified v = ( 1 1 1 2 2 2 3 3 3 )
Requirements
Header: <algorithm>
Namespace: std