Question

gcc 4.4.4 c89

I have seen this in some code I am maintaining.

#define FALSE 0
#define TRUE (!FALSE)

is there any difference in writing the following:

#define FALSE 0
#define TRUE 1

Its been used in some functions like this:

if(condition failed) {
    return FALSE;
}
else {
    return TRUE;
}

Many thanks for any suggestions,

Answer 1

One difference is, in the (!FALSE) case, if you change:

#define FALSE 0

to

#define FALSE 1

Your program still “works”, without modifying TRUE… however, it’s unlikely that would be safe anyways, because I’m sure your program relies on constructs such as

if (funtion_that_returns_FALSE()) {
}

Which would break if you changed the definition of FALSE. Don’t change it 🙂