std::counted_iterator<I>::operator++,+,+=,--,-,-=
From cppreference.com
< 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;
Parameters
| n | - | 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
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) }
See also
|
(C++20)
|
advances the iterator (function template) |
|
(C++20)
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computes the distance between two iterator adaptors (function template) |