Define Unambiguous Synonym

Understanding define unambiguous synonym requires examining multiple perspectives and considerations. c++ - What does ## in a #define mean? 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. From another angle, 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: What is the difference between #define and const? 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.

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++ - 'static const' vs.

'#define' - Stack Overflow. Another key aspect involves, 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? Moreover, c - #Define VS Variable - Stack Overflow.

#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 occurrence of the name is replaced by its associated text. From another angle, what is the purpose of the #define directive in C++?. #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 almost all the situations where you could use a #defined numerical constant, including array bounds. 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.