In other words, when the compiler starts building your code, no #define statements or anything like that is left. A good way to understand what the preprocessor does to your code is to get …

How can I use #if inside #define in the C preprocessor? Asked 15 years, 8 months ago Modified 9 months ago Viewed 51k times

The question is if users can define new macros in a macro, not if they can use macros in macros.

2009年11月4日 · Which one is better to use among the below statements in C? static const int var = 5; or #define var 5 or enum { var = 5 };

2011年5月14日 · What is the point of #define in C++? I've only seen examples where it's used in place of a "magic number" but I don't see the point in just giving that value to a variable instead.

2017年3月4日 · #define simply substitutes a name with its value. Furthermore, a #define 'd constant may be used in the preprocessor: you can use it with #ifdef to do conditional …

2010年5月10日 · 0 in C or C++ #define allows you to create preprocessor Macros. In the normal C or C++ build process the first thing that happens is that the PreProcessor runs, the …

2010年8月24日 · As the title says; what's the difference in practice between the inline keyword and the #define preprocessor directive?

2012年6月18日 · #define WIDTH 10 is a preprocessor directive that allows you to specify a name (WIDTH) and its replacement text (10). The preprocessor parses the source file and each …

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 …