向量的 cbegin 和 begin 有什么区别?

2022-01-10 00:00:00 iterator vector c++ stl

成员 begin 有两个重载，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
begin 将根据 const 返回 iterator 或 const_iterator- 调用它的对象的限定.

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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