NAME¶

std::counted_iterator::counted_iterator - std::counted_iterator::counted_iterator

Synopsis¶

constexpr counted_iterator() requires (1) (since C++20)
std::default_initializable<I> = default;
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> (3) (since C++20)

constexpr counted_iterator( const counted_iterator<I2>&
other );

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¶

// Run this code

#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¶

operator= assigns another iterator adaptor
(C++20) (public member function)