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std::reverse_iterator<Iter>::operator++,+,+=,--,-,-=

From cppreference.com
 
 
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
Utilities
(C++20)
Iterator adaptors
Stream iterators
Iterator customization points
Iterator operations
(C++11)
(C++11)
Range access
(C++11)(C++14)
(C++11)(C++14)
(C++17)(C++20)
(C++14)(C++14)
(C++14)(C++14)
(C++17)
(C++17)
 
std::reverse_iterator
Member functions
reverse_iterator::operator++reverse_iterator::operator+reverse_iterator::operator+=reverse_iterator::operator--reverse_iterator::operator-reverse_iterator::operator-=
Non-member functions
(C++20)
(C++20)
 
(1)
reverse_iterator& operator++();
(until C++17)
constexpr reverse_iterator& operator++();
(since C++17)
(2)
reverse_iterator& operator--();
(until C++17)
constexpr reverse_iterator& operator--();
(since C++17)
(3)
reverse_iterator operator++( int );
(until C++17)
constexpr reverse_iterator operator++( int );
(since C++17)
(4)
reverse_iterator operator--( int );
(until C++17)
constexpr reverse_iterator operator--( int );
(since C++17)
(5)
reverse_iterator operator+( difference_type n ) const;
(until C++17)
constexpr reverse_iterator operator+( difference_type n ) const;
(since C++17)
(6)
reverse_iterator operator-( difference_type n ) const;
(until C++17)
constexpr reverse_iterator operator-( difference_type n ) const;
(since C++17)
(7)
reverse_iterator& operator+=( difference_type n );
(until C++17)
constexpr reverse_iterator& operator+=( difference_type n );
(since C++17)
(8)
reverse_iterator& operator-=( difference_type n );
(until C++17)
constexpr reverse_iterator& operator-=( difference_type n );
(since C++17)

Increments or decrements the iterator. Inverse operations are applied to the underlying operator because of the reverse order.

1-2) Pre-increments or pre-decrements by one respectively.
3-4) Post-increments or post-decrements by one respectively.
5-6) Returns an iterator which is advanced by n or -n positions respectively.
7-8) Advances the iterator by n or -n positions respectively.

Contents

[edit] Parameters

n - position relative to current location.

[edit] Return value

1-2) *this.
3-4) a copy of *this that was made before the change.
5-6) reverse_iterator(base()-n) or reverse_iterator(base()+n) respectively.
7-8) *this.

[edit] Example

#include <iostream>
#include <iterator>
#include <list>
#include <vector>
 
int main()
{
    std::vector v {0, 1, 2, 3, 4};
    auto rv = std::reverse_iterator {v.rbegin()};
    std::cout << *(++rv) << ' '; // 3
    std::cout << *(--rv) << ' '; // 4
    std::cout << *(rv + 3) << ' '; // 1
    rv += 3;
    std::cout << rv[0] << ' '; // 1
    rv -= 3;
    std::cout << rv[0] << '\n'; // 4
 
    std::list l {5, 6, 7, 8};
    auto rl = std::reverse_iterator {l.rbegin()};
    std::cout << *(++rl) << ' '; // OK: 3
    std::cout << *(--rl) << ' '; // OK: 4
    // The following statements raise compilation error because the
    // underlying iterator does not model the random access iterator:
//  *(rl + 3) = 13;
//  rl += 3;
//  rl -= 3;
}

Output:

3 4 1 1 4
7 8

[edit] See also

advances the iterator
(function template) [edit]
computes the distance between two iterator adaptors
(function template) [edit]