Author: Vincent Diepeveen
Date: 10:13:33 06/07/04
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On June 07, 2004 at 10:40:09, Fabien Letouzey wrote: >On June 07, 2004 at 10:36:58, Vincent Diepeveen wrote: > >>On June 07, 2004 at 10:30:50, Fabien Letouzey wrote: > >>r = 1<<36; // works for good compilers not for the rest > >Hm, my understanding is that first "1<<36" should be calculated (so it's 0 if >sizeof(int) <= 4) and *then* cast into r's type (oops, too late). >Fabien. The result is undefined when integer = 32 bits and long long is 64 bits. Trivially it is a very natural thing to try to write r = 1 << 36 when using a 64 bits type; Needing to cast every non-integer is not a nice way of programming now that all processors are getting 64 bits, and 99% of all programmers will make mistakes with it, basically taking care C/C++ in the future is not a serious programming language. Because ansi-C definitely runs behind here on good programming habits, it's up to the compilers mercy whether it works or doesn't, so only good compilers will support it, as they support a natural way of working with the environment. The rule in ansi-C should read that for constants assigned, they should be assumed to have the same type and not that they should be assumed to be integer.
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