Practical C Programming

How to do it...

Follow these steps to perform conditional compilation with preprocessor directives:

1. Define a Qty macro and assign it an initial value:

#define Qty 10

2. The user will be prompted to enter the price of a book:

printf("Enter price of a book ");scanf("%f", &price);

3. The total number of books is computed using the Qty*price formula: 

totalAmount=Qty*price; 

4. On the basis of the Qty macro, the #if, #elif, #else, and #endif directives are used to determine the discount on the total number.
5. Once the discount percentage is determined, the amount after deducting the discount is computed and is assigned to the afterDisc variable:

afterDisc=totalAmount - (totalAmount*discount)/100; 

6. The festival discount is also computed on the ...