std::ranges::fill
From cppreference.com
| Defined in header <algorithm>
|
||
| Call signature |
||
| template< class T, std::output_iterator<const T&> O, std::sentinel_for<O> S > constexpr O |
(1) | (since C++20) |
| template< class T, ranges::output_range<const T&> R > constexpr ranges::borrowed_iterator_t<R> |
(2) | (since C++20) |
1) Assigns the given value to the elements in the range
[first, last).2) Same as (1), but uses r as the source range, as if using ranges::begin(r) as first and ranges::end(r) as last.
The function-like entities described on this page are niebloids, that is:
- Explicit template argument lists cannot be specified when calling any of them.
- None of them are visible to argument-dependent lookup.
- When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.
In practice, they may be implemented as function objects, or with special compiler extensions.
Parameters
| first, last | - | the range of elements to modify |
| r | - | the range of elements to modify |
| value | - | the value to be assigned |
Return value
An output iterator that compares equal to last.
Complexity
Exactly last - first assignments.
Possible implementation
struct fill_fn { template<class T, std::output_iterator<const T&> O, std::sentinel_for<O> S> constexpr O operator()(O first, S last, const T& value) const { while (first != last) *first++ = value; return first; } template<class T, ranges::output_range<const T&> R> constexpr ranges::borrowed_iterator_t<R> operator()(R&& r, const T& value) const { return (*this)(ranges::begin(r), ranges::end(r), value); } }; inline constexpr fill_fn fill; |
Example
The following code uses ranges::fill to set all elements of std::vector<int> first to -1, then to 10.
Run this code
#include <algorithm> #include <iostream> #include <vector> void println(std::vector<int> const& vi) { for (int e : vi) std::cout << e << ' '; std::cout << '\n'; } int main() { std::vector<int> v {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; std::ranges::fill(v.begin(), v.end(), -1); println(v); std::ranges::fill(v, 10); println(v); }
Output:
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 10 10 10 10 10 10 10 10 10 10
See also
| (C++20) |
assigns a value to a number of elements (niebloid) |
| (C++20)(C++20) |
copies a range of elements to a new location (niebloid) |
| (C++20) |
saves the result of a function in a range (niebloid) |
| (C++20) |
applies a function to a range of elements (niebloid) |
| copy-assigns the given value to every element in a range (function template) |