std::counted_iterator<I>::operator++,+,+=,--,-,-=

constexpr counted_iterator& operator++();	(1)	(since C++20)
constexpr decltype(auto) operator++( int );	(2)	(since C++20)
constexpr counted_iterator operator++( int ) requires std::forward_iterator<I>;	(3)	(since C++20)
constexpr counted_iterator& operator--() requires std::bidirectional_iterator<I>;	(4)	(since C++20)
constexpr counted_iterator operator--( int ) requires std::bidirectional_iterator<I>;	(5)	(since C++20)
constexpr counted_iterator operator+( std::iter_difference_t<I> n ) const requires std::random_access_iterator<I>;	(6)	(since C++20)
constexpr counted_iterator& operator+=( std::iter_difference_t<I> n ) requires std::random_access_iterator<I>;	(7)	(since C++20)
constexpr counted_iterator operator-( std::iter_difference_t<I> n ) const requires std::random_access_iterator<I>;	(8)	(since C++20)
constexpr counted_iterator& operator-=( std::iter_difference_t<I> n ) requires std::random_access_iterator<I>;	(9)	(since C++20)

Increments or decrements the underlying iterator current and the distance to the end length.

The behavior of these functions is undefined if the length would be set to a minus value.

1) Pre-increments by one. Equivalent to ++current; --length; return *this;.

2) Post-increments by one. Equivalent to --length; try { return current++; } catch(...) { ++length; throw; }.

3) Post-increments by one. Equivalent to counted_iterator temp{*this}; ++*this; return temp;.

4) Pre-decrements by one. Equivalent to --current; ++length; return *this;.

5) Post-decrements by one. Equivalent to counted_iterator temp{*this}; --*this; return temp;.

6) Returns an iterator adaptor which is advanced by n. Equivalent to return counted_iterator(current + n, length - n);.

7) Advances the iterator adaptor by n. Equivalent to current += n; length -= n; return *this;.

8) Returns an iterator adaptor which is advanced by -n. Equivalent to return counted_iterator(current - n, length + n);.

9) Advances the iterator adaptor by -n. Equivalent to current -= n; length += n; return *this;.

Parameters

the number of positions to increment or decrement the iterator adaptor

Return value

1) *this

2,3) A copy of *this that was made before the change.

4) *this

5) A copy of *this that was made before the change.

6) An iterator adaptor which is advanced by n.

7) *this

8) An iterator adaptor which is advanced by -n.

9) *this

Example

#include <cassert>
#include <initializer_list>
#include <iterator>
 
int main()
{
    const auto v = {1, 2, 3, 4, 5, 6};
    std::counted_iterator<std::initializer_list<int>::iterator> it1{v.begin(), 5};
 
    ++it1;              assert(*it1 == 2 && it1.count() == 4); // (1)
    auto it2 = it1++;   assert(*it2 == 2 && *it1 == 3);        // (3)
    --it1;              assert(*it1 == 2 && it1.count() == 4); // (4)
    auto it3 = it1--;   assert(*it3 == 2 && *it1 == 1);        // (5)
    auto it4 = it1 + 3; assert(*it4 == 4 && it4.count() == 2); // (6)
    auto it5 = it4 - 3; assert(*it5 == 1 && it5.count() == 5); // (8)
    it1 += 3;           assert(*it1 == 4 && it1.count() == 2); // (7)
    it1 -= 3;           assert(*it1 == 1 && it1.count() == 5); // (9)
}

operator+ (C++20)	advances the iterator (function template)
operator- (C++20)	computes the distance between two iterator adaptors (function template)

std::counted_iterator<I>::operator++,+,+=,--,-,-=

Parameters

Return value

Example

See also