c++ - What does ## in a #define mean? - Stack Overflow
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 …
c++ - Why use #define instead of a variable - Stack Overflow
May 14, 2011 · 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.
How can I use #if inside #define in the C preprocessor?
How can I use #if inside #define in the C preprocessor? Asked 15 years, 6 months ago Modified 8 months ago Viewed 51k times
What is the difference between #define and const? [duplicate]
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 to use the PI constant in C++ - Stack Overflow
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 …
c - #Define VS Variable - Stack Overflow
Jun 18, 2012 · #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 …
Difference between `constexpr` and `#define` - Stack Overflow
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 …
c++ - 'static const' vs. '#define' - Stack Overflow
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?
Why are #ifndef and #define used in C++ header files?
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?
What is the purpose of the #define directive in C++?
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 …