Macros

A macro is a sort of abbreviation which you can define once and then use later. There are many complicated features associated with macros in the C preprocessor.

• Simple Macros: Macros that always expand the same way.
• Argument Macros: Macros that accept arguments that are substituted into the macro expansion.
• Predefined: Predefined macros that are always available.
• Stringification: Macro arguments converted into string constants.
• Concatenation: Building tokens from parts taken from macro arguments.
• Undefining: Cancelling a macro's definition.
• Redefining: Changing a macro's definition.
• Macro Pitfalls: Macros can confuse the unwary. Here we explain several common problems and strange features.