For a very resource constrained target such as 4KB of RAM, I’d test the waters with some samples before committing a lot of effort that can’t be easily ported back into a pure ANSI C implementation. The Embedded C++ working group did propose a standard subset of the language and a standard subset of the … Read more
The section that allowed the implicit int rule in C89 would be section 3.5.2 Type specifiers which says (emphasis mine): int , signed , signed int , or no type specifiers Keith Thompson in the comments points out that in C90 the section is 6.5.2 and says, The only difference is some introductory material required … Read more
It’s just a way of creating a ‘harmless’ reference to the variable. The compiler doesn’t complain about an unused variable, because you did reference the value, and it doesn’t complain that you didn’t do anything with the value of the expression var because you explicitly cast it to void (nothing), indicating that you didn’t care … 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
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
That looks like K&R (pre-ANSI) style. I don’t think it’s valid C99, but are they using C99? Joel
There may be some confusion here about what “K&R C” is. The term refers to the language as documented in the first edition of “The C Programming Language.” Roughly speaking: the input language of the Bell Labs C compiler circa 1978. Kernighan and Ritchie were involved in the ANSI standardization process. The “ANSI C” dialect … Read more
You can find nice HTML versions of C89, C99, and C11, as well as some of the official draft PDF files they’re generated from, here: http://port70.net/~nsz/c/ Some other useful direct links to free PDF files of the C89/C90, C99 and C11 standards are listed below: C89/C90: https://www.pdf-archive.com/2014/10/02/ansi-iso-9899-1990-1/ansi-iso-9899-1990-1.pdf C99: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf C11: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
char is always a byte , but it’s not always an octet. A byte is the smallest addressable unit of memory (in most definitions), an octet is 8-bit unit of memory. That is, sizeof(char) is always 1 for all implementations, but CHAR_BIT macro in limits.h defines the size of a byte for a platform and … Read more
It’s not possible to do this in C: a function can’t return a pointer to itself, since the type declaration expands recursively and never ends. See this page for an explanation: http://www.gotw.ca/gotw/057.htm The workaround described on the above page means returning void (*) () instead of the correctly-typed function pointer; your workaround is arguably a … Read more