fill

Replaces each element with a given value

Definition

The fill() algorithm is defined in the standard header <algorithm> and in the nonstandard backward-compatibility header <algo.h>.

Interface

#include <algorithm>
template < class ForwardIterator, class Type >
   void fill(
      ForwardIterator first, 
      ForwardIterator last, 
      const Type& val
   );

Parameters:

Parameter	Description
first	A forward iterator addressing the position of the first element in the range to be traversed
last	A forward iterator addressing the position one past the final element in the range to be traversed
val	The value to be assigned to elements in the range `[first, last)`

Description

Fill algorithm fills a range with a given value by using operator=.

Return Value

None.

Complexity

The complexity is linear; performs (last - first) assignments.

References

http://www.tenouk.com/

Example 1

Problem

The following program demonstrates how to use fill() function.

Workings

#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
 
int main()
{
  vector <int> vec;
  vector <int>::iterator Iter1;
  int i;
  for (i = 10; i <= 20; i++)
    vec.push_back(i);
  cout <<"Vector vec data: ";
  for(Iter1 = vec.begin(); Iter1 != vec.end(); Iter1++)
    cout <<*Iter1<<" ";
  cout <<endl;
  // fill the last 4 positions with a value of 9
  cout <<"\nOperation: fill(vec.begin() + 4, vec.end(), 9)\n";
  fill(vec.begin() + 4, vec.end(), 9);
  cout <<"Modified vec data: ";
  for (Iter1 = vec.begin(); Iter1 != vec.end(); Iter1++)
    cout <<*Iter1<<" ";
  cout <<endl;
  
  return 0;
}

Solution

Output:

Vector vec data: 10 11 12 13 14 15 16 17 18 19 20
Operation: fill(vec.begin() + 4, vec.end(), 9)
Modified vec data: 10 11 12 13 9 9 9 9 9 9 9

References

http://www.tenouk.com/

Example 2

Problem

This program illustrates the use of the STL fill() algorithm to set all values in a range of values within a vector of integers to a given value.

Workings

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
  int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  vector<int> v(a, a+10);
  cout <<"\nHere are the contents of v:\n";
  for (vector<int>::size_type i=0; i<v.size(); i++)
    cout <<v.at(i)<<" ";

  cout <<"\nNow we set the 3rd to the 7th values of v to 20.";
  fill(v.begin()+2, v.begin()+7, 20);
  cout <<"\nHere are the revised contents of v:\n";
  for (vector<int>::size_type i=0; i<v.size(); i++)
    cout <<v.at(i)<<" ";

  cout <<"\nNow we set all values from the 6th on to -1.";
  fill(v.begin()+5, v.end(), -1);
  cout <<"\nHere are the revised contents of v:\n";
  for (vector<int>::size_type i=0; i<v.size(); i++)
    cout <<v.at(i)<<" ";

  cout <<"\nFinally, we initialize the entire vector to 0.";
  fill(v.begin(), v.end(), 0);
  cout <<"\nHere are the revised contents of v:\n";
  for (vector<int>::size_type i=0; i<v.size(); i++)
    cout <<v.at(i)<<" ";

  return 0;
}

Solution

Output:

Here are the contents of v:
1 2 3 4 5 6 7 8 9 10

Now we set the 3rd to the 7th values of v to 20.
Here are the revised contents of v:
1 2 20 20 20 20 20 8 9 10

Now we set all values from the 6th on to -1.
Here are the revised contents of v:
1 2 20 20 20 -1 -1 -1 -1 -1

Finally, we initialize the entire vector to 0.
Here are the revised contents of v:
0 0 0 0 0 0 0 0 0 0

References

http://www.smu.ca/academic/science/compsci/

Definition

Interface

Description

Return Value

Complexity

References

Example 1

Example 2

See Also