As far as I can see there are 3 ways to use booleans in c
#defin
I don't know you specific situation. Back when I was writing C programs, we have always used #2.
#define FALSE = 0
#define TRUE = !FALSE
This might be otherwise under alien platform to DOS or Intel-based processors. But I used to use both C and ASM together writing graphic libraries and graphical IDE. I was a true fan of Micheal Abrash and was intending to learn about texture mapping and so. Anyway! That's not the subject of the question here!
This was the most commonly used form to define boolean values in C, as this headerfile stdbool.h did not exist then.