Define State Enums And Transition Rules

May 14, 2011what is the point of #define in c++? How can i use #if inside #define in the c preprocessor? Nov 4, 2009which one is better to use among the below statements in c?

Static const int var = 5; Or #define var 5 or enum { var = 5 }; The question is if users can define new macros in a macro, not if they can use macros in macros.

In other words, when the compiler starts building your code, no #define statements or anything like that is left. The #define directive is a preprocessor directive; As far as i know, what you're trying to do (use if statement and then return a value from a macro) isn't possible in iso c.

But it is somewhat possible with statement expressions (gnu extension). Aug 24, 2010macros (created with #define) are always replaced as written, and can have double-evaluation problems. Jun 18, 2012#define width 10 is a preprocessor directive that allows you to specify a name (width) and its replacement text (10).

Mar 4, 2017#define simply substitutes a name with its value. Furthermore, a #define 'd constant may be used in the preprocessor: