这个bool操作符在C ++中实际上做了什么？ 这个奇怪的东西怎么有用呢？

Question

When I read C++ book I encountered with a strange operator !():

class myClass
{ 
     public:
bool operator !() const {}//What is it??
  };

Can someone explain me its purpose please.

Answer 1

That is an ill-formed program, taken that operator! is declared to return bool but does not return anything. With that being fixed, it is the negation operator and it can be called on an object by prefixing ! .

myClass c;
!c;         // c.operator!()

Answer 2

You can use it like this:

myClass some_obj;
...
if (!some_obj) {
  ...
}