# Directive #define

Directive #define

  `#define`

Description

  This directive is used to define or redefine a cpp macro.

  The simplest way to use define is to write

      #define <identifier> <replacement string>

  which will cause all subsequent occurances of `<identifier` to be replaced with the `<replacement string>`.

  Define also has the capability to use arguments, thus a line like

      #define <identifier>(arg1, arg2) <replacement string>

  would cause `<identifer>` to be a macro. All occurances of '`<identifier>(something1,something2d)`' would be replaced with the `<replacement string>`. And in the `<replacement string>`, `arg1` and `arg2` will be replaced with `something1` and `something2`.