Fortunately, Microsoft’s stance on this issue has changed. MSVC++ version 12.0 (part of Visual Studio 2013) added support for _Bool type. Compound literals. Designated initializers. Mixing declarations with code. __func__ predefined identifier. You can check the _MSC_VER macro for values greater than or equal to 1800 to see whether these features are supported. Standard library … Read more
There are 2 ways to do this: Variadric macro #define my_printf(…) printf(__VA_ARGS__) function that forwards va_args #include <stdarg.h> #include <stdio.h> void my_printf(const char *fmt, …) { va_list args; va_start(args, fmt); vprintf(fmt, args); va_end(args); } There are also vsnprintf, vfprintf and whatever you can think of in stdio.
Previous GCC versions have the -fipa-struct-reorg option to allow structure reordering in -fwhole-program + -combine mode. -fipa-struct-reorg Perform structure reorganization optimization, that change C-like structures layout in order to better utilize spatial locality. This transformation is affective for programs containing arrays of structures. Available in two compilation modes: profile-based (enabled with -fprofile-generate) or static (which … Read more
Anonymous unions are a GNU extension, not part of any standard version of the C language. You can use -std=gnu99 or something like that for c99+GNU extensions, but it’s best to write proper C and not rely on extensions which provide nothing but syntactic sugar… Edit: Anonymous unions were added in C11, so they are … Read more
In C1, they refer to the same type. C99 ยง6.2.1 defines the scopes that exist: 2 For each different entity that an identifier designates, the identifier is visible (i.e., can be used) only within a region of program text called its scope. Different entities designated by the same identifier either have different scopes, or are … Read more
I think you’re right, it’s not possible to implement memmove efficiently in standard C. The only truly portable way to test whether the regions overlap, I think, is something like this: for (size_t l = 0; l < len; ++l) { if (src + l == dst) || (src + l == dst + len … Read more
This is explained in depth in the gcc manual, available (if it’s installed) by typing info gcc or online here. The relevant section of the 4.7.2 manual is here. By default, gcc does not conform to any of the ANSI/ISO C standards. The current default is equivalent to -std=gnu90, which is the 1989/1990 standard with … Read more
State machines are very simple in C if you use function pointers. Basically you need 2 arrays – one for state function pointers and one for state transition rules. Every state function returns the code, you lookup state transition table by state and return code to find the next state and then just execute it. … Read more
That looks like K&R (pre-ANSI) style. I don’t think it’s valid C99, but are they using C99? Joel
Yes, as of C99, reaching the } at the end of main returns 0 if the return type of main is compatible with int. 5.1.2.2.3 Program termination If the return type of the main function is a type compatible with int, a return from the initial call to the main function is equivalent to calling … Read more