D. Preprocessor

Objectives

In this appendix you'll learn: To use #include for developing large programs. To use #define to create macros and macros with arguments. To understand conditional compilation. To display error messages during conditional compilation. To use assertions to test if the values of expressions are correct.

Hold thou the good; define it well.

—Alfred, Lord Tennyson

I have found you an argument; but I am not obliged to find you an understanding.

—Samuel Johnson

A good symbol is the best argument, and is a missionary to persuade thousands.

—Ralph Waldo Emerson

Conditions are fundamentally sound.

—Herbert Hoover [December 1929]

The partisan, when he is engaged in a dispute, cares nothing about the rights of the question, but is anxious only to convince his hearers of his own assertions.

—Plato

Outline

D.1 Introduction D.2 The #include Preprocessor Directive D.3 The #define Preprocessor Directive: Symbolic Constants D.4 The #define Preprocessor Directive: Macros D.5 Conditional Compilation D.6 The #error and #pragma Preprocessor Directives D.7 Operators # and ## D.8 Predefined Symbolic Constants D.9 Assertions D.10 Wrap-Up