std::fill

template <class ForwardIterator, class T>  void fill (ForwardIterator first, ForwardIterator last, const T& val);

Fill range with value

Assigns val to all the elements in the range [first,last).

The behavior of this function template is equivalent to:

template <class ForwardIterator, class T>
  void fill (ForwardIterator first, ForwardIterator last, const T& val)
{
  while (first != last) {
    *first = val;
    ++first;
  }
}

Parameters

first, last: Forward iterators to the initial and final positions in a sequence of elements that support being assigned a value of type T. The range filled is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
val: Value to assign to the elements in the filled range.

Return value

none

Example

// fill algorithm example
#include <iostream>     // std::cout
#include <algorithm>    // std::fill
#include <vector>       // std::vector

int main () {
  std::vector<int> myvector (8);                       // myvector: 0 0 0 0 0 0 0 0

  std::fill (myvector.begin(),myvector.begin()+4,5);   // myvector: 5 5 5 5 0 0 0 0
  std::fill (myvector.begin()+3,myvector.end()-2,8);   // myvector: 5 5 5 8 8 8 0 0

  std::cout << "myvector contains:";
  for (std::vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}

Output:

myvector contains: 5 5 5 8 8 8 0 0

Complexity

Linear in the distance between first and last: Assigns a value to each element.

Data races

The objects in the range [first,last) are modified (each object is accessed exactly once).

Exceptions

Throws if either an element assignment or an operation on an iterator throws.
Note that invalid arguments cause undefined behavior.