HP C/iX Reference Manual (31506-90011)

Chapter 7 105

Preprocessing Directives

Macro Replacement

operators that might be used with the MAX macro.

Using a macro deﬁnition for MAX has some advantages over a function deﬁnition. First, it

executes faster because the macro generates in-line code, avoiding the overhead of a

function call. Second, the MAX macro accepts any argument types. A functional

implementation of MAX would be restricted to the types deﬁned for the function. Note

further that because each argument to the MAX macro appears in the token string more

than once, check to be sure that the actual arguments to the MAX macro do not have any

"side effects." The following example

MAX(a, b);

might not work as expected because the argument a is incremented two times when a is

the maximum.

The following statement

i = MAX(a, b+2);

is expanded to:

i = ((a) > (b+2) ? (a) : (b+2));

Examples

#define isodd(n) ( ((n % 2) == 1) ? (TRUE) : (FALSE))

/* This macro tests a number and returns TRUE if the number is odd. It will

/* return FALSE otherwise.

#define eatspace() while( (c=getc(input)) ==''||c=='\n' || c == '\t' )

;

/* This macro skips white spaces.