C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  using uint64_t with GCC          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Richard Cavell Guest Posted: Sun Feb 27, 2005 12:13 pm    Post subject: using uint64_t with GCC uint64_t i64_BitMask = (uint64_t) (1 << 33) - 1 ; int a = (i64_BitMask >> 32); printf ("BitMask %xn", a); This produces ffffffff. I'm pretty sure, watching the stages in debugging, that 1 << 33 is resolving to zero, since it's being shifted off the MSB of a 32 bit integer. I am in general having problems with uint64_t with GCC. In particular, I can't send one to printf and get a sensible output. The shift operators appear to only work with 32-bit integers. Also, if I have intermediate steps, it always seems to want to truncate the output to 32-bits. Putting in casts to uint64_t sometimes fixes it, but not always. What do I do? (using XCode, Apple's stdint.h) Back to top jacob navia Guest Posted: Sun Feb 27, 2005 1:22 pm    Post subject: Re: using uint64_t with GCC Richard Cavell wrote: Quote: uint64_t i64_BitMask = (uint64_t) (1 << 33) - 1 ; The problem is that the expression (1 << 33) is calculated (as it should) in integer mode, i.e. 32 bits. The result (zero) is *THEN* cast to uint64_t. Fix: uint64_t i64_BitMask = (uint64_t) ((uint64_t)1 << 33) - 1 ; jacob Back to top Ron Natalie Guest Posted: Sun Feb 27, 2005 2:55 pm    Post subject: Re: using uint64_t with GCC jacob navia wrote: = Quote: uint64_t i64_BitMask = (uint64_t) ((uint64_t)1 << 33) - 1 ; You have an unneeded cast there. The left-most cast serves no purpose. Back to top jacob navia Guest Posted: Sun Feb 27, 2005 5:05 pm    Post subject: Re: using uint64_t with GCC Ron Natalie wrote: Quote: jacob navia wrote: = uint64_t i64_BitMask = (uint64_t) ((uint64_t)1 << 33) - 1 ; You have an unneeded cast there. The left-most cast serves no purpose. True. uint64_t i64_BitMask = ((uint64_t)1 << 33) - 1 ; is better. Also good is uint64_t i64_BitMask = (1LL << 33) - 1 ; jacob Back to top bachelor Guest Posted: Sun Feb 27, 2005 5:35 pm    Post subject: Re: using uint64_t with GCC i don't know why you need shifts, in some cases <bitset> is more elegant IMHO Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.