fill() function in C++ STL with examples

The fill() function in C++ STL is used to fill some default value in a container. The fill() function can also be used to fill values in a range in the container. It accepts two iterators begin and end and fills a value in the container starting from position pointed by begin and just before the position pointed by end.


void fill(iterator begin, iterator end, type value);


  • begin: The function will start filling values from the position pointed by the iterator begin.
  • end: The function will fill values upto the position just before the position pointed by the iterator end.
  • value: This parameter denotes the value to be filled by the function in the container.

NOTE : Notice carefully that ‘begin’ is included in the range but ‘end’ is NOT included.

Return Value: This function does not returns any value.

Below program illustrate the fill() function in C++ STL:





// C++ program to demonstrate working of fill()
#include <bits/stdc++.h>
using namespace std;
int main()
    vector<int> vect(8);
    // calling fill to initialize values in the
    // range to 4
    fill(vect.begin() + 2, vect.end() - 1, 4);
    for (int i = 0; i < vect.size(); i++)
        cout << vect[i] << " ";
    // Filling the complete vector with value 10
    fill(vect.begin(), vect.end(), 10);
    cout << endl;
    for (int i = 0; i < vect.size(); i++)
        cout << vect[i] << " ";
    return 0;



0 0 4 4 4 4 4 0 
10 10 10 10 10 10 10 10


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