fill, fill_n

     Algorithm

Initializes a range with a given value.

Contents

• Synopsis
• Description
• Complexity
• Example
• Warnings

#include <algorithm>

template <class ForwardIterator, class T>
  void fill(ForwardIterator first, ForwardIterator last,
            const T& value);
template <class OutputIterator, class Size, class T>
  void fill_n(OutputIterator first, Size n, const T& value);

The fill and fill_n algorithms are used to assign a value to the elements in a sequence. fill assigns the value to all the elements designated by iterators in the range [first, last).

The fill_n algorithm assigns the value to all the elements designated by iterators in the range [first, first + n). fill_n assumes that there are at least n elements following first, unless first is an insert iterator.

fill makes exactly last - first assignments, and fill_n makes exactly n assignments.

//
// fill.cpp
//
 #include <algorithm>
 #include <vector>
 #include <iostream.h>
 int main()
 {
   int d1[4] = {1,2,3,4};
   //
   // Set up two vectors
   //
   vector<int> v1(d1,d1 + 4), v2(d1,d1 + 4);
   //
   // Set up one empty vector
   //
   vector<int> v3;
   //
   // Fill all of v1 with 9
   //
   fill(v1.begin(),v1.end(),9);
   //
   // Fill first 3 of v2 with 7
   //
   fill_n(v2.begin(),3,7);
   //
   // Use insert iterator to fill v3 with 5 11's
   //
   fill_n(back_inserter(v3),5,11);
   //
   // Copy all three to cout
   //
   ostream_iterator<int> out(cout," ");
   copy(v1.begin(),v1.end(),out);
   cout << endl;
   copy(v2.begin(),v2.end(),out);
   cout << endl;
   copy(v3.begin(),v3.end(),out);
   cout << endl;
   //
   // Fill cout with 3 5's
   //
   fill_n(ostream_iterator<int>(cout," "),3,5);
   cout << endl;
   return 0;
 }
Output :
9 9 9 9
7 7 7 4
11 11 11 11 11
5 5 5

If your compiler does not support default template parameters then you need to always supply the Allocator template argument. For instance you'll have to write:

vector<int,allocator>

instead of:

vector<int>