c-preprocessor

Automatic class registration in C++ is a common task, and a commonly asked question here on StackOverflow: Register an object creator in object factory Somehow register my classes in a list automatic registration of object creator function with a macro c++ automatic factory registration of derived types The basic objective is to register classes automatically with some registry or factory so that it can do some work with each class later. This is a well-established technique, used by libraries like (for example) Google Test ( http://code.google.com/p/googletest ), which automatically registers

This question already has answers here : How to mark java code such that it's not compiled [duplicate] (9 answers) Possible Duplicate: How to mark java code such that it’s not compiled In c , we can prevent compilation of block code like this : #if 0 //code here #endif So even if code block is error prone the code compiles, I want the same thing in Java, So that I can skip that part of code which won't compile because some library is missing. Can anyone help me ? You have to comment out the code , you can't use pre-processor directive in java. There is no preprocessor in Java. Depending on

A hypothetical question: Is it possible to have a C++ program, which includes preprocessor directives, entirely on one line? Such a line would look like this: #define foo #ifdef foo #define bar #endif What are the semantics of such a line? Further, are there any combinations of directives which are impossible to construct on one line? If this is compiler-specific then both VC++ and GCC answers are welcome. A preprocessing directive must be terminated by a newline, so this is actually a single preprocessing directive that defines an object-like macro, named foo , that expands to the following

Back a long time ago I used to use pre-compiled headers: a. to speed compilation and b. because I supported multiple development tools like CodeWarrior, MPW, VS, ProjectBuilder, gcc, intel compilers, etc, etc. Now I have a Mac Pro with 32gb of RAM. Now I use just CMake. So do we really need pre-compiled headers any more? Are there obvious benefits that I just dont see/know? How can one make a cross-platform pre-compiled header? Maybe that would simplify my life too. There is no such thing as a build that is "Fast enough". Proponents of TDD ( Test-Driven Development ) will be upset if their

Is there a #define compiler (nvcc) macro of CUDA which I can use? (Like _WIN32 for Windows and so on.) I need this for header code that will be common between nvcc and VC++ compilers. I know I can go ahead and define my own and pass it as an argument to the nvcc compiler (-D), but it would be great if there is one already defined. __CUDACC__ I don't think it will be that trivial. Check the following thread http://forums.nvidia.com/index.php?showtopic=32369&st=0&p=179913&#entry179913 N. Pattakos I know it has been long time now, but you might also find __CUDA_ARCH__ useful. 来源： https:/

This question already has an answer here: Array-size macro that rejects pointers 9 answers Finding the size of a static array is a common operation. see: C find static array size - sizeof(a) / sizeof((a)[0]) This can be wrapped into a macro, eg: #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0])) however its possible to accidentally pass in a regular pointer. eg: void func(SomeArray **foo) { int i = ARRAY_SIZE(foo); } While its valid C, but often ends up being a logical error. Its possible to prevent this mistake (taking advantage of per-processor to fail on a zero length bit-field) . #define