Thread: Writing a macro to compare two numbers?

Originally Posted by RichSelian

I want such a macro in my project: cmp(x, y) returns a positive number when x > y, a negative number when x < y, and 0 when x == y. of course I know the simplest way:

Code:

#define cmp(x, y) (((x) > (y)) ? 1 : (((x) == (y)) ? 0 : -1))

but this cannot work properly for the code like cmp(x++, y++). Can this limit be fixed?

Do you really care if it returns 1, 0 or -1? If all you care about is a positve, 0 or negative value you can simply return (x - y);

Code:

#define cmp(x, y) (x - y)

Originally Posted by grumpy

That won't work if x and y are both of unsigned integral type.

Picky picky picky!

But you're right it won't work on unsigned values...
But then it was only an example, intended to convey an idea...