std::fill (3) - Linux Manuals

std::fill: std::fill

NAME

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