std::counted_iterator<I>::operator++,+,+=,--,-,-=
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< cpp | iterator | counted iterator
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;.
Contents |
[edit] Parameters
n | - | the number of positions to increment or decrement the iterator adaptor |
[edit] 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
[edit] Example
Run this code
#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) }
[edit] See also
(C++20) |
advances the iterator (function template) |
(C++20) |
computes the distance between two iterator adaptors (function template) |