Define Affecting Vs Effecting

In recent times, define affecting vs effecting has become increasingly relevant in various contexts. 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.

It's important to note that, c++ - 'static const' vs. '#define' - Stack Overflow. 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?

Building on this, 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. 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. c++ - Declaring a function using #define - Stack Overflow. The #define version is still a macro.

The code is expanded at the invocation site. It has all the expected problems (with macros) including namespace pollution and unexpected parameter behaviour. What's the difference in practice between inline and #define?.

Macros (created with #define) are always replaced as written, and can have double-evaluation problems. inline on the other hand, is purely advisory - the compiler is free to ignore it. Under the C99 standard, an inline function can also have external linkage, creating a function definition which can be linked against. answered Aug 24, 2010 at 8 ...