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(cpp-295.info)Macros

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Macros
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   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.

Macro Varargs

Macros with variable number of arguments.

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.