Short answer: Use macros and #ifdef checking. For example: #ifdef MY_CONTROL_MACRO … #endif the code within this scope will only be compiled if you already defined the MY_CONTROL_MACRO macro. More stuff: To define such a macro, you can Add #define MY_CONTROL_MACRO to your code. Or, For VS, add MY_CONTROL_MACRO to Project > Properties > C/C++ … Read more
Imagine you wrote this: #define Max(a,b) (a < b ? b : a) int x(){ turnLeft(); return 0; } int y(){ turnRight(); return 1; } then called it like this: auto var = Max(x(), y()); Do you know that turnRight() will be executed twice? That macro, Max will expand to: auto var = (x() < … Read more
First I’ve heard of it. No; #define and so on are widely used. Sometimes too widely used, but definitely used. There are places where the C standard mandates the use of macros — you can’t avoid those easily. For example, §7.5 Errors <errno.h> says: The macros are EDOM EILSEQ ERANGE which expand to integer constant … Read more
Yes, we can. The #endif statement matches to the previous #if #ifdef or #ifndef etc for which there hasn’t been a corresponding #endif. e.g. #if ———-| #if —–| | #endif —| | #endif ——–|
Yes. Pass gcc the -E option. This will output preprocessed source code.
Yes you can do it. In Swift you can still use the “#if/#else/#endif” preprocessor macros (although more constrained), as per Apple docs. Here’s an example: #if DEBUG let a = 2 #else let a = 3 #endif Now, you must set the “DEBUG” symbol elsewhere, though. Set it in the “Swift Compiler – Custom Flags” … Read more