cbegin和vector之间的区别是什么？ [英] What is the difference between cbegin and begin for vector?

问题描述

会员开始有两个超载，其中一个是 const_iterator begin（）const; 。还有 cbegin const_iterator cbegin（）const noexcept ; 。它们都将 const_iterator 返回到列表的开头。有什么区别？

The member begin has two overloadings one of them is const_iterator begin() const;. There's also the cbegin const_iterator cbegin() const noexcept;. Both of them returns const_iterator to the begin of a list. What's the difference?

推荐答案

开始将返回 iterator 或 const_iterator ，具体取决于调用它的对象的const限定。

begin will return an iterator or a const_iterator depending on the const-qualification of the object it is called on.

cbegin 将无条件地返回 const_iterator 。

std::vector<int> vec;
const std::vector<int> const_vec;

vec.begin(); //iterator
vec.cbegin(); //const_iterator

const_vec.begin(); //const_iterator
const_vec.cbegin(); //const_iterator

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