Conditional Compilation: (#if and #else directives). The block of code will be processed based on expression result.

L8Q4_if_else_directives.c

#include<stdio.h>
# define TEST 5
int main(){

    # if TEST < 5
        printf("TEST is smaller than 5.");
    # elif TEST == 5
        printf("TEST is equal to 5.");
    # else
        printf("TEST is greater than 5.");
    # endif // TEST
        printf("\n Good guess!");
}