Illustrated C# 2012

C H A P T E R  23

Preprocessor Directives

• What Are Preprocessor Directives?
• General Rules
• The #define and #undef Directives
• Conditional Compilation
• The Conditional Compilation Constructs
• Diagnostic Directives
• Line Number Directives
• Region Directives
• The #pragma warning Directive

What Are Preprocessor Directives?

The source code specifies the definition of a program. The preprocessor directives instruct the compiler how to treat the source code. For example, under certain conditions, you might want the compiler to ignore portions of the code, and under other conditions, you might want that code compiled. The preprocessor directives give you those options and several others.

In C and C++ there is an actual preprocessor phase, in which the preprocessor ...