enum defines a syntactical element. #define is a pre-preprocessor directive, executed before the compiler sees the code, and therefore is not a language element of C itself. Generally enums are preferred as they are type-safe and more easily discoverable. Defines are harder to locate and can have complex behavior, for example one piece of code … Read more
It basically tells the compiler that the class RootViewController exists, without specifying what exactly it looks like (ie: its methods, properties, etc). You can use this to write code that includes RootViewController member variables without having to include the full class declaration. This is particularly useful in resolving circular dependencies – for example, where say … Read more
You can print out the value of a preprocessor variable under visual studio. The following prints out the value of _MSC_VER: #define STRING2(x) #x #define STRING(x) STRING2(x) #pragma message(STRING(_MSC_VER)) Not sure how standard this is though.
It has no type. It is a simple text substitution. The text 5000 will be dropped in place wherever MAXLINE appears as a token. For example: int a = MAXLINE; will put the value 5000 in a. While char *MAXLINE2 = “MAXLINE”; will not result in char *50002 = “5000”; So, if you want type-checking, … Read more
In this context (applied to a parameter reference in a macro definition), the pound sign means to expand this parameter to the literal text of the argument that was passed to the macro. In this case, if you call PRINT(5) the macro expansion will be printf(“5” “%d\n”, 5); which will print 5 5; not very … Read more
When referencing to header files relative to your c file you should use #include “path/to/header.h” The form #include <someheader.h> is only used for internal headers or for explicitly added directories (in gcc with the -I option).
It’s _MSC_VER. More info at MSDN and at predef. But, be aware that some other compilers may also define it, e.g. Intel’s C++ Compiler for Windows also defines _MSC_VER. If this is a concern, use #if _MSC_VER && !__INTEL_COMPILER.
He who is Shy* gave you the germ of an answer, but only the germ. The basic technique for converting a value into a string in the C pre-processor is indeed via the ‘#’ operator, but a simple transliteration of the proposed solution gets a compilation error: #define TEST_FUNC test_func #define TEST_FUNC_NAME #TEST_FUNC #include <stdio.h> … Read more
help macro You must compile with the -g3 flag for it to work and start your program before the macros are loaded. In your case: info macro CONST or macro expand CONST More info: http://sourceware.org/gdb/current/onlinedocs/gdb/Macros.html
It is compiler dependent and may differ between enums. The following are the semantics enum X { A, B }; // A has type int assert(sizeof(A) == sizeof(int)); // some integer type. Maybe even int. This is // implementation defined. assert(sizeof(enum X) == sizeof(some_integer_type)); Note that “some integer type” in C99 may also include extended … Read more