operator std::string() const?

Question

Can somebody tell me what precisely

operator std::string()

stands for?

Answer 1

It is a cast operator. Any class that defines this type can be used anywhere a std::string is required. For instance,

class Foo {
public:
    operator std::string() const { return "I am a foo!"; }
};
...
Foo foo;
std::cout << foo; // Will print "I am a foo!".

Cast operators are almost always a bad idea, since there is invariably a better way to achieve the same result. In the above case, you are better off defining operator<<(std::ostream&, const Foo&).