Namespaces
Variants

std::counted_iterator<I>:: operator[]

From cppreference.net
C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
std::counted_iterator
constexpr decltype ( auto ) operator [ ] ( std:: iter_difference_t < I > n ) const
requires std:: random_access_iterator < I > ;
(C++20 起)

访问指定相对位置的元素。若 n 不小于到末尾的记录距离，则行为未定义。

目录

参数

n - 相对于当前位置的偏移量

返回值

this - > base ( ) [ n ]

示例

运行此代码 
#include <array>
#include <iostream>
#include <iterator>
#include <list>
int main()
{
    std::array array{'A', 'B', 'C', 'D', 'E'};
    std::counted_iterator it{array.begin() + 1, /*count:*/ 3};
    for (int i{}; i != it.count(); ++i)
        std::cout << it[i] << ' ';
    std::cout << '\n';
    for (int i{}; i != it.count(); ++i)
        it[i] += ('E' - 'A');
    for (int i{}; i != it.count(); ++i)
        std::cout << it[i] << ' ';
    std::cout << '\n';
    std::list list{'X', 'Y', 'Z', 'W'};
    std::counted_iterator it2{list.begin(), 3};
//  char x = it2[0]; // Error: requirement `random_access_iterator` was not satisfied.
    std::cout << *it2 << '\n'; // OK
}

输出： 

B C D
F G H
X

参见

访问所指向的元素
(公开成员函数)