Const指针与类

类的成员函数在调用的时候,会有一个隐式的this指针,默认情况下,这个指针的类型是 ClassName * const this,这意味着this指针不能改变,但this指针指向的对象是可以改变的。

但如果成员函数不会改变对象本身,那么this指针应该被设计为const ClassName * const this,即this指针是一个指向常量的常量指针,其指向的对象不可变更,本身也不可变更。

但因为this是隐式的指针,那么当我们想要声明this指针指向的对象是常量时,我们在哪里声明呢?

就在成员函数的参数后面,加一个const。这就叫常量成员函数。

注意,常量的对象无法调用自身的非常量成员函数,原因就在于,非常量成员函数的this指针是:ClassName * const this,无法指向一个const的对象。

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