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operator+ (std::reverse_iterator)

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Iterator library
Iterator concepts
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Algorithm concepts and utilities
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(C++17)
std::reverse_iterator
定义于头文件 <iterator>
template < class Iter >

reverse_iterator < Iter > operator +
( typename reverse_iterator < Iter > :: difference_type n,

const reverse_iterator < Iter > & it ) ;
(自 C++17 起为 constexpr)
(C++23 前)
template < class Iter >

constexpr reverse_iterator < Iter > operator +

( std:: iter_difference_t < Iter > n, const reverse_iterator < Iter > & it ) ;
(自 C++23 起)

返回迭代器 it 增加 n 后的结果。实际上，底层迭代器会递减 n 次。

目录

参数

n - 要递增迭代器的位置数量
it - 要递增的迭代器适配器

返回值

reverse_iterator < Iter > ( it. base ( ) - n )

示例

运行此代码 
#include <iostream>
#include <iterator>
#include <list>
#include <vector>
int main()
{
    {
        std::vector v{0, 1, 2, 3};
        std::reverse_iterator<std::vector<int>::iterator>
            ri1{std::reverse_iterator{v.rbegin()}};
        std::cout << *ri1 << ' '; // 3
        std::reverse_iterator<std::vector<int>::iterator> ri2{2 + ri1};
        std::cout << *ri2 << ' '; // 1
    }
    {
        std::list l{5, 6, 7, 8};
        std::reverse_iterator<std::list<int>::iterator>
            ri1{std::reverse_iterator{l.rbegin()}};
        std::cout << *ri1 << '\n'; // 8
    //  auto ri2{2 + ri1}; // 错误：底层迭代器不满足随机访问迭代器要求
                           //        model random access iterator
    }
}

输出： 

3 1 8

参见

递增或递减 reverse_iterator
(公开成员函数)
计算两个迭代器适配器间的距离
(函数模板)