Chapter 11: The Preprocessor – Macros and Conditional Compilation

Table of Contents

• Table of Contents
• 11.1 Macros
• 11.2 Conditional Compilation
• 11.3 Exercises
• 11.4 Solutions
  • 11.4.1 Solution 1
  • 11.4.2 Solution 2
  • 11.4.3 Solution 3
• 11.5 What’s Coming in the Next Chapter

11.1 Macros

Macros are code shortcuts:

#define PI 3.14

11.2 Conditional Compilation

Use #ifdef, #ifndef, #endif to include/exclude code:

#ifdef DEBUG
    printf("Debug mode\n");
#endif

11.3 Exercises

1. Define a macro for the square of a number.
2. Use conditional compilation to print a message only if DEBUG is defined.
3. What is the difference between #define and const?

11.4 Solutions

11.4.1 Solution 1

#define SQUARE(x) ((x)*(x))

11.4.2 Solution 2

#ifdef DEBUG
    printf("Debug!\n");
#endif

11.4.3 Solution 3

#define is handled by the preprocessor; const is handled by the compiler.

11.5 What’s Coming in the Next Chapter

Next, you’ll learn about bitwise operations in C!

Next Chapter → Bitwise Operations – Ones, Zeros, and Mind Tricks