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
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
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
There is in C99, but not in previous standards AFAIK. In C99, you’ll have NAN and INFINITY macros. From “Mathematics <math.h>“ (§7.12) section The macro INFINITY expands to a constant expression of type float representing positive or unsigned infinity, if available; … If you’re stuck with ANSI C89, you’re out of luck. See C-FAQ 14.9.
It depends on what you mean by ‘truly standards compliant’. However, the short answer is “it is a good idea to ensure that all functions have a prototype in scope before being used”. A more qualified answer notes that if the function accepts variable arguments (notably the printf() family of functions), then a prototype must … Read more
In C99, it’s technically undefined behavior. C99 §6.5.6 says: 7) For the purposes of these operators, a pointer to an object that is not an element of an array behaves the same as a pointer to the first element of an array of length one with the type of the object as its element type. … Read more
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
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
The strncpy() function was designed with a very particular problem in mind: manipulating strings stored in the manner of original UNIX directory entries. These used a short fixed-sized array (14 bytes), and a nul-terminator was only used if the filename was shorter than the array. That’s what’s behind the two oddities of strncpy(): It doesn’t … Read more
As the C FAQ says: It’s not clear if it’s legal or portable, but it is rather popular. and: … an official interpretation has deemed that it is not strictly conforming with the C Standard, although it does seem to work under all known implementations. (Compilers which check array bounds carefully might issue warnings.) The … Read more