Std::fill (3) Linux Manual Page

std::fill – std::fill

Synopsis

Defined in header<algorithm>

    template <class ForwardIt, class T>
    (until C++ 20)

        void fill(ForwardIt first, ForwardIt last, const T &value);

template <class ForwardIt, class T>
(1)(since C++ 20)

    constexpr void fill(ForwardIt first, ForwardIt last, const T &value);

template <class ExecutionPolicy, class ForwardIt, class T>
(2)(since C++ 17)

    void fill(ExecutionPolicy &&policy, ForwardIt first, ForwardIt last, const T &value);

1) Assigns the given value to the elements in the range [first, last).
2) Same as (1), but executed according to policy. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true

Parameters

first, last – the range of elements to modify
value – the value to be assigned
policy – the execution policy to use. See execution_policy for details.

Type requirements

–
ForwardIt must meet the requirements of LegacyForwardIterator.

Return value

(none)

Complexity

Exactly last – first assignments.

Exceptions

The overload with a template parameter named ExecutionPolicy reports errors as follows:

* If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard_policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
* If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation

  template< class ForwardIt, class T >
  void fill(ForwardIt first, ForwardIt last, const T& value)
  {
      for (; first != last; ++first) {
          *first = value;
      }
  }

Example

The following code uses fill() to set all of the elements of a vector of integers to -1:
// Run this code

#include <algorithm>

#include <vector>

#include <iostream>
int main()

{
    std::vector<int> v{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    std::fill(v.begin(), v.end(), -1);
    for (auto elem : v) {
        std::cout << elem << " ";
    }
    std::cout << "\n";
}

Output:

-1 -1 -1 -1 -1 -1 -1 -1 -1 -1

std::fill (3) Linux Manual Page