Practical C Programming, 3rd Edition

The ( ) operator can be overloaded for a class to give the class a "default" function. For example:

class example { public: int operator ( ) (int i) { return (i * 2); } }; // .... example example_var; j = example_var(3); // j is assigned the value 6 (3 * 2)

Overloading the ( ) operator is rarely done. Normal member functions can easily be used for the same purpose but have the advantage of providing the user with a function name .