std::ranges::fill() algorithm
- od C++20
- Simplified
- Detailed
// (1)
template<
class T,
std::output_iterator<const T&> O,
std::sentinel_for<O> S
>
constexpr O fill( O first, S last, const T& value );
// (2)
template<
class T,
ranges::output_range<const T&> R
>
constexpr ranges::borrowed_iterator_t<R> fill( R&& r, const T& value );
The type of arguments are generic and have the following constraints:
T
- (none)O
-std::output_iterator<const T&>
S
-std::sentinel_for<O>
- (2) -
R
-std::ranges::output_range<const T&>
// (1)
template<
class T,
std::output_iterator<const T&> O,
std::sentinel_for<O> S
>
constexpr O fill( O first, S last, const T& value );
// (2)
template<
class T,
ranges::output_range<const T&> R
>
constexpr ranges::borrowed_iterator_t<R> fill( R&& r, const T& value );
- (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 usingranges::begin(r)
asfirst
andranges::end(r)
aslast
.
The function-like entities described on this page are niebloids.
Parameters
first last | The range of elements to examine. |
r | The range of elements to examine. |
value | The value to assign. |
Return value
An output iterator that compares equal to last
.
Complexity
Exactly last - first
assignments.
Exceptions
(none)
Possible implementation
ranges::fill
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;
Examples
The following code uses ranges::fill
to set all elements of std::vector<int>
first to -1
, then to 10
.
#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);
}
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1
10 10 10 10 10 10 10 10 10 10
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