operator+(std::counted_iterator)
From cppreference.com
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.
Parameters
| n | - | the number of positions to increment the iterator |
| x | - | the iterator adaptor to increment |
Return value
An iterator adaptor equal to x + n.
Example
Run this code
#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