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Groups > comp.lang.c > #105182
| From | Lowell Gilbert <lgusenet@be-well.ilk.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | "usual arithmetic conversions": please explain something... |
| Date | 2017-02-28 18:33 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <448topoppn.fsf@be-well.ilk.org> (permalink) |
Given the following program:
#include <stdio.h>
int main (void)
{
unsigned long a = 4000;
signed long b = -10;
int c;
c = a * b;
printf("%d\n", c);
return 0;
}
I am surprised that I get a negative answer. From reading the standard,
my expectation was that the multiplication would convert the signed
operand to unsigned, based on this bit of the standard:
Otherwise, if the operand that has unsigned integer type has rank greater or
equal to the rank of the type of the other operand, then the operand with
signed integer type is converted to the type of the operand with unsigned
integer type.
They've got the same rank, right?
What am I missing? [It must be something, because I don't even get
warnings on any of several compilers, with messages cranked up high.]
--
Lowell Gilbert, embedded/networking software engineer
http://be-well.ilk.org/~lowell/
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"usual arithmetic conversions": please explain something... Lowell Gilbert <lgusenet@be-well.ilk.org> - 2017-02-28 18:33 -0500
Re: "usual arithmetic conversions": please explain something... BartC <bc@freeuk.com> - 2017-02-28 23:45 +0000
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-02-28 16:59 -0800
Re: "usual arithmetic conversions": please explain something... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-01 02:20 +0000
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-02-28 18:51 -0800
Re: "usual arithmetic conversions": please explain something... BartC <bc@freeuk.com> - 2017-03-01 12:04 +0000
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-03-01 08:25 -0800
Re: "usual arithmetic conversions": please explain something... BartC <bc@freeuk.com> - 2017-03-01 16:47 +0000
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-03-01 09:43 -0800
Re: "usual arithmetic conversions": please explain something... BartC <bc@freeuk.com> - 2017-03-01 18:00 +0000
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-03-01 10:15 -0800
Re: "usual arithmetic conversions": please explain something... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-01 19:08 +0000
Re: "usual arithmetic conversions": please explain something... supercat@casperkitty.com - 2017-03-01 09:01 -0800
Re: "usual arithmetic conversions": please explain something... jameskuyper@verizon.net - 2017-02-28 15:49 -0800
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-02-28 16:03 -0800
Re: "usual arithmetic conversions": please explain something... Nick Bowler <nbowler@draconx.ca> - 2017-03-01 21:53 +0000
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-03-01 14:18 -0800
Re: "usual arithmetic conversions": please explain something... Lowell Gilbert <lgusenet@be-well.ilk.org> - 2017-03-01 08:29 -0500
Re: "usual arithmetic conversions": please explain something... Lowell Gilbert <lgusenet@be-well.ilk.org> - 2017-03-01 09:11 -0500
Re: "usual arithmetic conversions": please explain something... Keith Thompson <kst-u@mib.org> - 2017-03-01 08:59 -0800
Re: "usual arithmetic conversions": please explain something... scott@slp53.sl.home (Scott Lurndal) - 2017-03-01 14:00 +0000
Re: "usual arithmetic conversions": please explain something... "James R. Kuyper" <jameskuyper@verizon.net> - 2017-03-01 10:58 -0500
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