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 …

Mar 28, 2018 · 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 …

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 …

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 …

Jul 9, 2018 · #define is part of something called the "preprocessor." Essentially, this is the code that is processed before the C document is compiled. Most of the preprocessor code is in a file …

These two aren't equivalent: * In the first example, 'b' is still a positional argument that must be provided: * in the second example, 'b' is a true optional argument that can be ommitted (and in …

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 …

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 …

#define will declare HEADERFILE_H once #ifndef generates true. #endif is to know the scope of #ifndef i.e end of #ifndef. If it is not declared, which means #ifndef generates true, then only …