std::counted_iterator<I>::counted_iterator
constexpr counted_iterator() requires std::default_initializable<I> = default; |
(1) | (since C++20) |
constexpr counted_iterator( I x, std::iter_difference_t<I> n ); |
(2) | (since C++20) |
template< class I2 >
requires std::convertible_to<const I2&, I>
constexpr counted_iterator( const counted_iterator<I2>& other ); |
(3) | (since C++20) |
Constructs a new iterator adaptor.
1) Default constructor.
Value-initializes the underlying iterator and initialized the underlying
length with
0. Operations on the resulting iterator have defined behavior if and only if the corresponding operations on a value-initialized
I also have defined behavior.
2) The underlying iterator is initialized with
std::move(x) and the underlying
length is initialized with
n. The behavior is undefined if
n is negative.
3) The underlying iterator and
length are initialized with those of
other.
Parameters
| x | - | iterator to adapt |
| n | - | distance to the end |
| other | - | iterator adaptor to convert |
Example
#include <algorithm>
#include <initializer_list>
#include <iostream>
#include <iterator>
int main() {
static constexpr auto pi = {3, 1, 4, 1, 5, 9, 2};
// (1) default constructor:
constexpr std::counted_iterator<std::initializer_list<int>::iterator> i1{};
static_assert(i1 == std::default_sentinel);
static_assert(i1.count() == 0);
// (2) initializes the iterator and length respectively:
constexpr std::counted_iterator<std::initializer_list<int>::iterator> i2{
pi.begin(), pi.size() - 2
};
static_assert(i2.count() == 5);
static_assert(*i2 == 3 && i2[1] == 1);
// (3) converting-constructor:
std::counted_iterator<std::initializer_list<const int>::iterator> i3{i2};
std::ranges::copy(i3, std::default_sentinel,
std::ostream_iterator<const int>{std::cout, " "});
}
Output:
3 1 4 1 5
See also
|
(C++20)
|
assigns another iterator adaptor (public member function) |
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