You have used
if(num=0)
instead of
if(num==0)
Edit:
You probably want an
else if
in there as well
#include <stdio.h>
int main()
{
int num;
scanf("%d", &num);
if(num==0) {
printf("The num is %d", num);
} else if(num % 2 == 0) {
printf("The num %d is even.", num);
} else {
printf("The num %d is odd.", num);
}
return 0;
}