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 …
Is it possible to use a if statement inside #define?
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 …
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.
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 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 7 months ago Viewed 51k times
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 …
How to declare variable and use it in the same Oracle SQL script?
I want to write reusable code and need to declare some variables at the beginning and reuse them in the script, such as: DEFINE stupidvar = 'stupidvarcontent'; SELECT stupiddata FROM …
How do I define a function with optional arguments?
How do I define a function with optional arguments? Asked 13 years, 8 months ago Modified 1 year, 4 months ago Viewed 1.2m times
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?
c preprocessor - Is there a good reason for always enclosing a …
#define _add_penguin(a) penguin ## a #define add_penguin(a) _add_penguin(a) #define WIDTH (100) #define HEIGHT 200 add_penguin(HEIGHT) // expands to penguin200 …