An enum is guaranteed to be represented by an integer, but the actual type (and its signedness) is implementation-dependent. You can force an enumeration to be represented by a signed type by giving one of the enumerators a negative value: enum SignedEnum { a = -1 }; In C++0x, the underlying type of an enumeration …
The struct you’re returning is not an anonymous struct. The C standard defines an anonymous struct as a member of another struct that doesn’t use a tag. What you’re returning is a struct without a tag, but since it isn’t a member, it is not anonymous. GCC uses the name < anonymous > to indicate …
Include <stdbool.h> header #include <stdbool.h> int main(void){ bool b = false; } Macros true and false expand to 1 and 0 respectively. Section 7.16 Boolean type and values < stdbool.h > 1 The header <stdbool.h> deļ¬nes four macros. 2 The macro bool expands to _Bool. 3 The remaining three macros are suitable for use in …
glibc uses libnss to support a number of different providers for address resolution services. Unfortunately, you cannot statically link libnss, as exactly what providers it loads depends on the local system’s configuration.
Good overviews of C11 standard: https://en.wikipedia.org/wiki/C11_(C_standard_revision) http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf https://smartbear.com/blog/test-and-monitor/c11-a-new-c-standard-aiming-at-safer-programming/ The standard includes several changes to the C99 language and library specifications, such as: Alignment specification (_Alignas specifier, _Alignof operator, aligned_alloc function, <stdalign.h> header file) The _Noreturn function specifier and the <stdnoreturn.h> header file Type-generic expressions using the _Generic keyword. For example, the following macro cbrt(x) translates …
See also What are extern variables in C. This is mentioned in the C standard in informative Annex J as a common extension: J.5.11 Multiple external definitions There may be more than one external definition for the identifier of an object, with or without the explicit use of the keyword extern; if the definitions disagree, …
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 …
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 …
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 …
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 …