如何访问在另一个类中声明的类？
问题描述：
我有一个简单的课程：
class cup{
public:
cup();
void drinkwater(water *t); // error occurs here
private:
class water{
public:
int litres;
};
};
但是我收到一个错误，说'water'有没有办法访问类，而不必把水类外面？
However I get an error saying that 'water' has not been declared. Is there any way to access the class without having to put the water class outside?
答
向前声明 class water; $ c>在 drinkwater 的定义之上的私有部分，例如
Forward-declare class water; in a private section above the definition of drinkwater, like
class cup{
class water;
public:
cup();
void drinkwater(water *t); // error occurs here
private:
class water{
public:
int litres;
};
};