Question

I have the following macro:

#define testMethod(a, b) \
        if (a.length > b.length) \
            return a; \
        return b;

When I try to call it with:

NSString *s = testMethod(@"fir", @"sec");

I get an error:

"Excepted ";" at end of declaration"

Why?

Answer 1

if is a statement, not an expression. It can’t return a value like that.

You probably mean:

#define testMethod(a, b) ((a).length > (b).length ? (a) : (b))

The extra parenthesis around the arguments on the right side are common, and are there to protect you against unexpected precendence-related incidents.

Also note that because the above is pre-processed by doing textual replacement, it will probably construct more objects than the equivalent function would.