1. Chapter 11: The Preprocessor

2. Introduction
Is a program that processes the source code before it passes through the compiler.
AKA preprocessor command line or pre-processor directives
Are placed in the source program before main line
All begin with #
Example: #include, #define, #typedef ….

3. Set of commonly used preprocessor
#include: specifies the files to be included
#define: defines macro substitution
#undef: Undefines a macro
#ifdef : Test for maco definition
#endif: Specifies the end of #if
#ifndef: Test whether a macro not defined
#if: Test a complete time condition
#else: Specifies alternative when #if test fails

4. Types Macro substitution directives File inclusion directives
Compiler control directives

5. Macro Substitution
The key word #define followed by identifier and string
Eg: #define FALSE 0
# define PI 3.14
# define CAPITAL “KATHMANDU”
Types:
SIMPLE
ARGUMENTED
NESTED

6. SIMPLE
Previous slide example are all simple
No argumented
Eg: 1

7. Macros with arguments Pass argument with macro Eg 2:
Some commonly used are
#define MAX(a,b) (((a)>(b))?(a):(b))
#define MIN(a,b) (((a)<(b))?(a):(b))
#define ABS(a,b) (((a)>0)?(a):(-(a))

8. Nesting of Macro #define SQUARE(X) ((X)*(X))
#define CUBE(X) (SQUARE(X)*(X))

9. File Inclusion We have already used it to include file
Eg: #include <stdio.h>
#include ”TEST.c”

10. Compiler control Directive