On 03/01/2021 22:59, John L. Males via Gcc-help wrote: > Hello, > > My question is not a need for programming assistance. My > question is to understand what the standard is for C with > respect to my questions. I have discovered a possible issue, > but want to ask questions first of expected C standard with > regards to my questions and if there are any related GCC > extensions to the questions. > I don't really think this is the best place to ask about C standards, but I'll try to give you some pointers. If you think there are issues about gcc's standards compliance, then of course this is a good starting point for discussing them. For details about the C (and C++) standards, I recommend this site: <https://en.cppreference.com/w/> It covers just about everything that the standards themselves cover, but is a good deal easier to navigate and read. >From this you can see: <https://en.cppreference.com/w/c/language/integer_constant> Binary literals (such as 0b01001011) are planned for the future C23 standard, but are not included in any current C standard. (From the matching C++ page you can see they were standardised in C++14, along with optional separators such as 0b0100'1011.) For details about gcc, the gcc manual is available online for a range of versions: <https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/Binary-constants.html> There are also many options in gcc for picking different standards - both "real" C standards and gcc extended "standards": <https://gcc.gnu.org/onlinedocs/gcc-9.3.0/gcc/C-Dialect-Options.html> > For the purposes of the questions the variable is an uint32_t. > > 1) What is the way to assign a bit value to variable? There are /many/ ways to do this - this is a basic C question, not a gcc question. > > 2) What is the format specifier to print a bit value with? printf format specifiers are part of the C standard: <https://en.cppreference.com/w/c/io/fprintf> Different implementations of printf can have extensions with other format specifiers, but that is up to the implementation of the library, not the compiler. gcc is a compiler, not a complete toolchain - it has no printf. So if you are using a library on a POSIX system, you'll have the POSIX extensions to printf documented here: <https://pubs.opengroup.org/onlinepubs/9699919799/functions/fprintf.html> Maybe there will be more - it depends on the library. But I don't know of any printf implementation that supports printing binary numbers directly. > > 3) What will (2) print like? > > To be clear these questions are not abut programming > assistance, but what is the C standard and/or GCC extension. > > (Why did you include piles of data about your system? Did you think the C standards depend on the temperature of your cpu?)
