fill() and fill_n() functions in C++ STL

// C++ program for displaying the default initialization
// of the vector vect[]
#include<bits/stdc++.h>
using namespace std;

int main() 
{
    // Creating a vector of size 8
    vector<int> vect(8);  

    // Printing default values
    for (int i=0; i<vect.size(); i++)
       cout << ' ' << vect[i];
}

// C++ program for displaying specified initialization
// of the vector vect[]
#include<bits/stdc++.h>
using namespace std;

int main () 
{
    // Creates a vector of size 8 with all initial
    // values as 1.
    vector<int> vect(8, 1);  

    for (int i=0; i<vect.size(); i++)
       cout << ' ' << vect[i];
}

// 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] << " ";

  return 0;
}

// C++ program to demonstrate working of fil_n()
#include <bits/stdc++.h>
using namespace std;

int main()
{
    vector<int> vect(8);  

    // calling fill to initialize first four values
    // to 7
    fill_n(vect.begin(), 4, 7);

    for (int i=0; i<vect.size(); i++)
        cout << ' ' << vect[i];
    cout << '\n';

    // calling fill to initialize 3 elements from 
    // "begin()+3" with value 4
    fill_n(vect.begin() + 3, 3, 4);

    for (int i=0; i<vect.size(); i++)
        cout << ' ' << vect[i];
    cout << '\n';

    return 0;
}