C Primer Plus, Fourth Edition

Using Arguments with #define

By using arguments, you can create function-like macros that look and act much like functions. A macro with arguments looks very similar to a function because the arguments are enclosed within parentheses. Function-like macro definitions have one or more arguments in parentheses, and these arguments then appear in the replacement portion, as shown in Figure 16.2.

Figure 16.2. Parts of a function-like macro definition.

Here's a sample definition:

#define SQUARE(X) X *X

It can be used in program like this:

z = SQUARE(2);

This looks like a function call, but it doesn't necessarily behave identically. Listing 16.2 ...