std::fill

If value is not writable to first, the program is ill-formed.

[edit] Parameters

[edit] Complexity

Exactly std::distance (first, last) assignments.

[edit] 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.

[edit] Possible implementation

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

[edit] Notes

[edit] Example

#include <algorithm>
#include <complex>
#include <iostream>
#include <vector>
 
void println(const auto& seq)
{
 for (const auto& e : seq)
 std::cout << e << ' ';
 std::cout << '\n';
}
 
int main()
{
 std::vector <int> v{0, 1, 2, 3, 4, 5, 6, 7, 8};
 println(v);
 
 // set all of the elements to 8
 std::fill(v.begin(), v.end(), 8);
 println(v);
 
 std::vector <std::complex <double>> nums{{1, 3}, {2, 2}, {4, 8}};
 println(nums);
 #ifdef __cpp_lib_algorithm_default_value_type
 std::fill(nums.begin(), nums.end(), {4, 2});
 #else
 std::fill(nums.begin(), nums.end(), std::complex <double>{4, 2});
 #endif
 println(nums);
}

0 1 2 3 4 5 6 7 8
8 8 8 8 8 8 8 8 8
(1,3) (2,2) (4,8) 
(4,2) (4,2) (4,2)

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also