I have code in one of the source file as follows: #include <stdio.h> #include <math.h> int a ; int b = 256 ; int c = 16 ; int d = 4 ; int main() { if ((d <= (b) && (d == ( c / sizeof(a)))) { printf("%d",sizeof(a) ); } return 0; } I have removed the casts and have simplified on the data names. The sizeof(a) can be taken as 4. I want to know if the the if syntax is a valid one and if so why doesn't it execute? PS : I haven't sat down on this for long due to time constraints. Pardon me if you find a childish error in the code.