if (!0) {
   printf("False: Zero\n");
}
if (-16) { 
   printf("True: Non-Zero\n");
}
printf("False: empty string %s\n", (3 < 2));
printf("True (Relational):  %d \n", (3 > 1));

False: Zero
True: Non-Zero
False: empty string 
True (Relational):  1