Preprocessor Directives

• A program which processes the source code before it passes through the compiler is known as preprocessor.
• The commands of the preprocessor are known as preprocessor directives.
• It is placed before the main().
• It begins with a # symbol.
• They are never terminated with a semicolon.

There are 3 Main Types of Preprocessor Directives:  

1. Macros
2. File Inclusion
3. Conditional Compilation