Listings 10.1 and 10.2 accomplish the same thing, but the overloaded functions in Listing 10.1 are easier to understand and more natural to use. Also, if a third variation is needed—perhaps the user wants to supply either the width or the height, but not both—it is easy to extend the overloaded functions. The default value, however, will quickly become unusably complex as new variations are added.

How do you decide whether to use function overloading or default values? Here’s a rule of thumb:

Use function overloading when

· There is no reasonable default value.

· You need different algorithms.

· You need to support variant types in your parameter list.