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 …

The #define directive is a preprocessor directive; the preprocessor replaces those macros by their body before the compiler even sees it. Think of it as an automatic search and replace of your …

How can I use #if inside #define in the C preprocessor? Asked 15 years, 6 months ago Modified 8 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.

Nov 13, 2009 · I want to use the PI constant and trigonometric functions in some C++ program. I get the trigonometric functions with include <math.h>. However, there doesn't seem to be …

Feb 12, 2021 · So I read the interesting answers about what are the differences between constexpr and const but I was curious about are the differences between #define and …

May 10, 2010 · #define to define numerical constants can be easily replaced by a const "variable", that, as a #define, doesn't really exist in the compiled executable. AFAIK it can be used in …

Oct 28, 2009 · Is it better to use static const variables than #define preprocessor? Or does it maybe depend on the context? What are advantages/disadvantages for each method?

I have been seeing code like this usually in the start of header files: #ifndef HEADERFILE_H #define HEADERFILE_H And at the end of the file is #endif What is the purpose of this?

Mar 4, 2017 · #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 compilation …