friend constexpr counted_iterator operator+(
std::iter_difference_t<I> n, const counted_iterator& x )
requires std::random_access_iterator<I>;
| (since C++20) |
Returns an iterator adaptor which is advanced by n. The behavior is undefined if n is greater than the length recorded within x (i.e. if x + n result in undefined behavior).
This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::counted_iterator<I> is an associated class of the arguments.
| n | - | the number of positions to increment the iterator |
| x | - | the iterator adaptor to increment |
An iterator adaptor equal to x + n.
#include <iostream>
#include <iterator>
#include <list>
#include <vector>
int main()
{
std::vector v { 0, 1, 2, 3, 4, 5 };
std::counted_iterator<std::vector<int>::iterator> p{ v.begin() + 1, 4 };
std::cout << "*p:" << *p << ", count:" << p.count() << '\n';
std::counted_iterator<std::vector<int>::iterator> q{ 2 + p };
std::cout << "*q:" << *q << ", count:" << q.count() << '\n';
std::list l { 6, 7, 8, 9 };
std::counted_iterator<std::list<int>::iterator> r{ l.begin(), 3 };
std::cout << "*r:" << *r << ", count:" << r.count() << '\n';
// auto s { 2 + r }; // error: the underlying iterator does
// not model std::random_access_iterator
}Output:
*p:1, count:4 *q:3, count:2 *r:6, count:3
|
(C++20) | advances or decrements the iterator (public member function) |
|
(C++20) | computes the distance between two iterator adaptors (function template) |
|
(C++20) | computes the signed distance to the end (function template) |
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