This is compiler dependent, I’m supposing you’re using GCC. You could check your compiler defined macros using: gcc -dM -E – < /dev/null Check the manual about the flags, specially: ###__STDC_VERSION__### This macro expands to the C Standard’s version number, a long integer constant of the form yyyymmL where yyyy and mm are the year … Read more
int is a “most efficient type” in speed/size – but that is not specified by per the C spec. It must be 16 or more bits. int_fast16_t is most efficient type in speed with at least the range of a 16 bit int. Example: A given platform may have decided that int should be 32-bit … Read more
The sizeof is an operator, not a function, and as any operator it has a precedence, which is in C lower than of the ++ operator. Therefore the construct sizeof(a)++ is equivalent to sizeof a++ which is in turn equivalent to sizeof (a++). Here we have postincrement on a which is an lvalue so it … Read more
Passing arrays to functions is a bit funny in C and C++. There are no rvalues of array types, so you’re actually passing a pointer. To address a 2D array (a real one, not array of arrays), you’ll need to pass 2 chunks of data: the pointer to where it starts how wide one row … Read more
Explicitly enabling POSIX features The timespec comes from POSIX, so you have to ‘enable’ POSIX definitions: #if __STDC_VERSION__ >= 199901L #define _XOPEN_SOURCE 600 #else #define _XOPEN_SOURCE 500 #endif /* __STDC_VERSION__ */ #include <time.h> void blah(struct timespec asdf) { } int main() { struct timespec asdf; return 0; } The stanza at the top is what … Read more
#include <inttypes.h> #include <stdint.h> printf(“%016” PRIxPTR “\n”, (uintptr_t)ptr); but it won’t print the pointer in the implementation defined way (says DEAD:BEEF for 8086 segmented mode).
If you spend a little time in the library, you don’t have to speculate. Here are some statements taken from Dennis Ritchie’s paper on the evolution of C. The context is that Dennis is building on Ken Thompson’s language B, which was implemented on the very tiny PDP-7, a word-addressed machine. Because of growing interest, … Read more
If you want to write portable C code, then I’d suggest you to write in C89 (old ANSI C standard). This standard is supported by most compilers. The Intel C Compiler has very good C99 support and it produces fast binaries. (Thanks 0x69!) MSVC supports some new features and Microsoft plan to broaden support in … Read more
In the very beginning of C the available memory and CPU resources were really scarce. So it had to compile really fast with minimal memory requirements. Therefore the C language has been designed to require only a very simple compiler which compiles fast. This in turn lead to “single-pass compiler” concept: The compiler reads the … Read more
Not sure about uint32_t, but for fundamental types (bool, char, signed char, unsigned char, wchar_t, short, unsigned short, int, unsigned int, long, unsigned long, float, double and long double) you can use the numeric_limits templates via #include <limits>. cout << “Minimum value for int: ” << numeric_limits<int>::min() << endl; cout << “Maximum value for int: … Read more