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Re: Application Exercises

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Malcolm McLean <malcolm.arthur.mclean@gmail.com> wrote:
> On Thursday, 11 April 2019 14:08:07 UTC+1, John Forkosh  wrote:
>> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>> > mark.bluemel@gmail.com writes:
>> > 
>> >> On Sunday, 7 April 2019 07:55:40 UTC+1, Tim Rentsch  wrote:
>> >>
>> >>> ram@zedat.fu-berlin.de (Stefan Ram) writes:
>> >>>
>> >>>> |Write a function to detect whether two integral numbers are
>> >>>> |equal without using any comparison operators.
>> >>>
>> >>> I have written a solution that I believe works correctly
>> >>> on any conforming implementation.
>> >>
>> >> But it's too large to fit in this margin?
>> > 
>> > Actually I wrote several solutions.  But I wasn't really
>> > happy with any of them, they were all a bit clunky in one
>> > way or another.  The point of my comment is just to say
>> > a fully portable solution is possible.
>> 
>> Didn't anybody just write...
>> 
>> /* --- test whether or not two ints are equal,
>>    without comparisons --- */
>> #include <stdio.h>
>> #include <stdlib.h>
>> int main ( int argc, char *argv[] ) {
>>   int  i = (argc>1? atoi(argv[1]) : 1 ),
>>        j = (argc>2? atoi(argv[2]) : 2 );
>>   int  isequal();
>>   fprintf( stdout," %d %s %d? \n",
>>        i, (isequal(i,j)?"==":"=/="), j);
>>   } /* --- end-of-function main() --- */
>> 
>> int isequal ( int i, int j ) {
>>   return ( !( abs(i-j) ) );
>>   } /* --- end-of-function isequal() --- */
>> 
>> Works fine on my box.
>>
> If both i is negative and j positive and large, this can generate an
> arithmetical overflow error

Sheesh! I didn't think that the -extremely-bleeping-pedantic compiler
switch was the point of the exercise:)  So how about
     return ( !( abs(abs(i)-abs(j)) ) );   ???
-- 
John Forkosh  ( mailto:  j@f.com  where j=john and f=forkosh )

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Re: Application Exercises Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-04-06 23:55 -0700
  Re: Application Exercises mark.bluemel@gmail.com - 2019-04-08 00:33 -0700
    Re: Application Exercises Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-04-09 04:28 -0700
      Re: Application Exercises John Forkosh <forkosh@panix.com> - 2019-04-11 13:07 +0000
        Re: Application Exercises Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-04-11 06:11 -0700
          Re: Application Exercises John Forkosh <forkosh@panix.com> - 2019-04-11 13:19 +0000
            Re: Application Exercises James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-04-11 06:49 -0700
              Re: Application Exercises Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-04-12 01:20 +0100
      Re: Application Exercises Richard Damon <Richard@Damon-Family.org> - 2019-04-11 23:36 -0400
        Re: Application Exercises Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-04-12 19:08 -0700

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