Why use C typedefs rather than #defines?

Question

What advantage (if any) is there to using typedef in place of #define in C code?

As an example, is there any advantage to using

typedef unsigned char UBYTE

over

#define UBYTE unsigned char

when both can be used as

void func()
{
        UBYTE byte_value = 0;

        /* Do some stuff */

        return byte_value;
}

Obviously the pre-processor will try to expand a #define wherever it sees one, which wouldn't happen with a typedef, but that doesn't seem to me to be any particular advantage or disadvantage; I can't think of a situation where either use wouldn't result in a build error if there was a problem.

Answer 1

1) Probably the great advantage is a cleaner code. Usually abusing macros transforms the code in an unmaintainable mess, known as: 'macro soup'.

2) By using a typedef you define a new type. Using a macro you actually substitute text. The compiler is surely more helpful when dealing with typedef errors.

Answer 2

If you do a typedef of an array type, you'll see the difference:

typedef unsigned char UCARY[3];
struct example { UCARY x, y, z; };

Doing that with a #define... no, let's not go there.

[EDIT]: Another advantage is that a debuggers usually know about typedefs but not #defines.