Author: Miguel A. Ballicora
Date: 15:14:09 01/10/03
Go up one level in this thread
On January 10, 2003 at 17:26:52, Robert Hyatt wrote: >On January 10, 2003 at 15:58:29, Miguel A. Ballicora wrote: > >>On January 10, 2003 at 15:06:58, Robert Hyatt wrote: >> >>>On January 10, 2003 at 12:37:20, Miguel A. Ballicora wrote: >>> >>>>On January 10, 2003 at 11:10:07, Robert Hyatt wrote: >>>> >>>>>On January 10, 2003 at 05:12:04, David Rasmussen wrote: >>>>> >>>>>>On January 09, 2003 at 17:36:11, Robert Hyatt wrote: >>>>>> >>>>>>>I think the entire concept of "short", "int" and "long" are badly flawed. It >>>>>>>would >>>>>>>have been so much more logical and clean to simply go with int16, int32 and >>>>>>>int64. >>>>>>> >>>>>>>I don't personally like "long long" as it is a syntactical oddity in light of >>>>>>>char, short, int >>>>>>>and float/double. >>>>>> >>>>>>There is a reasonable explanation for this at least. The idea is that "int" >>>>>>should be whatever is the most natural entity of integer calculalation on a >>>>>>machine. In many cases, you don't care how many bits a type can store. The lower >>>>>>limits given by the standards is enough. You just want to know that by writing >>>>>>"int" you get something that on every platform is supposed to be simple, fast, >>>>>>signed (no weird problems with subtraction etc.), >>>>> >>>>>But _not_ for "real codes". Do I _really_ want to use int, when it _might_ be a >>>>>16 bit value that won't hold the counter I need? >>>>> >>>>>No. >>>> >>>>You can use long, as you say below, if you really need bigger values than the >>>>ones provided by 16 bits. I do not think this is a big deal. >>>> >>>>Miguel >>> >>> >>>That's the point. On a Cray, I want to use "int" and get 32 bits, vs using long >>>and getting >> >>Just use int :-) > >Won't work. > >I need a 32 bit counter. I need a 64 bit bitboard. I need a 16 bit index. Use int, long (or long long) and int, respectively. I fail to see the the problem. >What works on the Cray will fail on the PC, because "long" works for the >Cray/Alpha but not for the PC if I want a 64 bit integer... If you want portable code, use long long for both. If it is a very important variable use typedef. >>If you have int16, int32, int64, you never know which one is more suitable for >>another processor. Suppose that int16 is enough and you use it, maybe int32 was >>faster! > >However, IO do know which is most suitable for _my_ application. If I need 64, >I >want 64, not whatever the compiler says is "best"... Then you sacrifice performance. Particularly for machines that do not have 8 bit chars and weird configurations! The performance hit in those cases is must be huge. You cannot have 100% portability and best performance at the same time. C gives, IMHO, the best compromise. History showed that. BTW, there is no problem in using a 32 bit integer if you only need 16. Miguel > > > >> >>Of course you have to make a decision if you want portable code or faster code. >>You can always use a typedef for a particular variable and have the best >>compromise in C. >>You cannot have 100% portable and optimal code in any scheme, even in the one >>you suggest. >> >>Miguel >> >> >> >> >>>64. I _know_ the precision I need, I'd prefer to be able to specify it >>>_precisely_ rather than >>>letting the compiler assume something.
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