在成员函数结束时const的含义是什么？ [英] What is the meaning of a const at end of a member function?

问题描述

C ++中的 const 关键字是什么意思，当它写在成员函数的结尾（在参数列表之后）？

What exactly does the const keyword in C++ mean when it's written at the end of a member function (after the argument list)?

推荐答案

这意味着 * this 是 const

关键字 this 是一个prvalue表达式，其值是调用函数的对象的地址。类 X 的成员函数中的类型 X c $ c>。如果成员函数声明为 const ，则 this 的类型为 const X * 。 [section 9.3.2§1]

The keyword this is a prvalue expression whose value is the address of the object for which the function is called. The type of this in a member function of a class X is X*. If the member function is declared const, the type of this is const X*. [section 9.3.2 §1]

在一个 const 成员函数中，函数被调用的对象通过 const 访问路径访问;因此， const 成员函数不应修改对象及其非静态数据成员。 [section 9.3.2§2]

In a const member function, the object for which the function is called is accessed through a const access path; therefore, a const member function shall not modify the object and its non-static data members. [section 9.3.2 §2]

这意味着 const 函数可以在类的 const 实例上调用。不能在 ^[1] a const 上调用非成员函数对象，因为它可能尝试修改它。

This means that a const member function can be called on a const instance of the class. A non-const member function can't be called on ^[1]a const object, since it could potentially try to modify it.

^{[1] 注意： const 对象，除非它是 const 类型。}

^{[1] Note: a temporary is not a const object unless it's of const type.}

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