Overloading Summary

We now have three ways to overload (some) operators

As a member function (required for some operators)
As a non-member function
As a (non-member) friend function

but some restrictions apply and some guidelines dictate which way is best (but not always).

Restrictions

Not all operators can be overloaded.
You can't make up your own operators.
You can't overload operators for primitive types.
You can't change the precedence of an operator.
You can't change the associativity of an operator.

Good Programming Practice

Overload operators so that they mimic the behavior of primitive data types.
Overloaded binary arithmetic operators should
- return const objects by value
- be written as non-member functions when appropriate to allow commutativity
- be written as non-friend functions (if data member accessors are available)
Overload unary operators as member functions.
Always overload<<
Overload operator= if your class uses dynamic memory allocation

Exercises for the student

Using the code for the Money class from the text, write the prototypes and implementations for other overloaded operators. Be sure to try comparison operators like <, >, !=, etc. and arithemtic operators like += and -=. Also try some unary operators such as ++ and --.

Last Modified: Monday, 28-Aug-2006 10:15:53 EDT