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- 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 hold of the preprocessed output and look at it
- 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, 7 months ago Modified 8 months ago Viewed 51k times
- What is the purpose of the #define directive in C++?
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 preprocessor looks though the source files for preprocessor directives like #define or #include and then performs simple operations with them
- c++ - Why use #define instead of a variable - Stack Overflow
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 define a define in C? - Stack Overflow
The question is if users can define new macros in a macro, not if they can use macros in macros
- Why do most C developers use define instead of const?
#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 based on its value, or use the stringizing operator # to get a string with its value
- 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 source code A const variable declaration declares an actual variable in the language, which you can use well, like a real variable: take its address, pass it around, use it, cast convert it, etc Oh
- 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 extension) Since #define s are essentially just fancy text find-and-replace, you have to be really careful about how they're expanded I've found that this works on gcc and clang by default:
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