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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
- Difference between `constexpr` and `#define` - Stack Overflow
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 constexpr ? I feel like constexpr is jus
- c preprocessor - Is there a good reason for always enclosing a define . . .
#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 add_penguin(WIDTH) error, cannot concatenate penguin and (100) Same for stringization (#) Clearly this is a corner case and probably doesn't matter considering how WIDTH will presumably be used Still, it is something to keep in
- What is the scope of a #define? - Stack Overflow
What is the scope of a #define? I have a question regarding the scope of a #define for C C++ and am trying to bet understand the preprocessor Let's say I have a project containing multiple sour
- c# - How do you use #define? - Stack Overflow
8 #define is used to define compile-time constants that you can use with #if to include or exclude bits of code
- How do I show the value of a #define at compile-time?
I know that this is a long time after the original query, but this may still be useful This can be done in GCC using the stringify operator "#", but it requires two additional stages to be defined first #define XSTR(x) STR(x) #define STR(x) #x The value of a macro can then be displayed with: #pragma message "The value of ABC: " XSTR(ABC) See: 3 4 Stringification in the gcc online
- c - How do I concatenate #define value? - Stack Overflow
You'll need to complete a few actions and gain 15 reputation points before being able to upvote Upvoting indicates when questions and answers are useful What's reputation and how do I get it? Instead, you can save this post to reference later
- 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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