为什么我的编译器在我重载增量运算符时会出错

Question

I am facing a problem in operator overloading, when I compile my program it gives me an error, following is the code:

class box
{
    int length;
    int width;
    int volume;
public:
    box():length(50),width(30)
    {

    }

    box& operator++()
    {
         volume++;
         width++;
         length++;
    }
};

int main()
{
    box b1;

    cout<<++b1;
}

The error it gives me is:

"no match for operator <<"

My question is why does the compiler give me an error although my syntax seems good?

Answer 1

Two problems:

1. Return *this from your overloaded operator.

2. If you want to print your object using "cout << ", you need to overload operator <<, otherwise print each member individually.