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 …

Nov 27, 2015 · 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 …

May 14, 2011 · Most compilers will allow you to define a macro from the command line (e.g. g++ -DDEBUG something.cpp), but you can also just put a define in your code like so: #define …

Jun 18, 2012 · The scope of #define is limited to the file in which it is defined. So, #defines which are created in one source file are NOT available in a different source file. In short, #defines …

Aug 24, 2010 · 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 …

You could indeed perform those check, at the cost of increased volume and complexity of code. The pythonic way is to assume the happy path (all types correct) is being followed, and cross …

Aug 19, 2008 · #define is used to define compile-time constants that you can use with #if to include or exclude bits of code. #define USEFOREACH #if USEFOREACH foreach(var item in …

Oct 28, 2009 · #define is a compiler pre processor directive and should be used as such, for conditional compilation etc.. E.g. where low level code needs to define some possible …

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 …

Feb 12, 2021 · Statements defined using #define are called macros. And macros are used in a multitude of uses. We can use them to conditionally compile sections of code. #ifdef ONE int …