Dear All,

Greetings!

I has been an hour I starting making my hands dirty with D. I wrote following program:

import std.string;
import std.stdio;

ushort adder(ushort a, ushort b) {
   return (cast(ushort)(a + b)) ;
}

unittest {

   bool testStimEq(ushort a, ushort b, ushort result){

      try {
         writefln(" STIM :: Testing for  %d  and  %d", a,b);
         assert(adder(a,b) == result);
         writefln(" STAT :: Test for  %d  and  %d passed", a,b);
         return (false) ;
      } catch (core.exception.AssertError) {
         writefln(" STAT :: Test for  %d  and  %d failed", a,b);
         return(true) ;
      }

   }

   bool testStimnEq(ushort a, ushort b, ushort result){

      try {
         writefln(" STIM :: Testing for  %d  and  %d", a,b);
         assert(adder(a,b) != result);
         writefln(" STAT :: Test for  %d  and  %d passed", a,b);
         return (false) ;
      } catch (core.exception.AssertError) {
         writefln(" STAT :: Test for  %d  and  %d failed", a,b);
         return(true) ;
      }

   }

   writeln(" MESG :: Starting unit testing");

   int status = 0 ;

   //status += testStimEq(1,1,2);
   //status += testStimnEq(1,10,3);

   for (ushort i = 0 ; i < 65536 ; ++i){ // Holy King-Kong!

      for (ushort j = 0 ; j < 65536 ; ++j){

         status += testStimEq(i,j,cast(ushort)(i+j));

      }
   }

   if(status == 0) writeln(" MESG :: All unit tests passed");
   else            writeln(" ERRN :: Unit test failed");

}

void main()
   {}

I found that inner for loop is behaving correctly, but i is not changing.
What is that I am doing ? OR is it gcd ?

Regards, Sumit

On Sunday, 27 October 2013 at 09:05:06 UTC, Sumit Adhikari wrote:
>    for (ushort i = 0 ; i < 65536 ; ++i){ // Holy King-Kong!
>
>       for (ushort j = 0 ; j < 65536 ; ++j){
>
>          status += testStimEq(i,j,cast(ushort)(i+j));
>
>       }
>    }
> What is that I am doing ?

You have an infinite loop nested within another infinite loop, ushort cannot represent a value which is >= 65536.

On Sunday, 27 October 2013 at 09:33:32 UTC, safety0ff wrote:
> On Sunday, 27 October 2013 at 09:05:06 UTC, Sumit Adhikari wrote:
>>   for (ushort i = 0 ; i < 65536 ; ++i){ // Holy King-Kong!
>>
>>      for (ushort j = 0 ; j < 65536 ; ++j){
>>
>>         status += testStimEq(i,j,cast(ushort)(i+j));
>>
>>      }
>>   }
>> What is that I am doing ?
>
> You have an infinite loop nested within another infinite loop, ushort cannot represent a value which is >= 65536.

Oops, missed that i & j is 16 bit!. Thanks for pointing that out

Regards, Sumit

Am Sun, 27 Oct 2013 10:40:01 +0100
schrieb "Sumit Adhikari" <sumit.adhikari@gmail.com>:

> On Sunday, 27 October 2013 at 09:33:32 UTC, safety0ff wrote:
> > On Sunday, 27 October 2013 at 09:05:06 UTC, Sumit Adhikari wrote:
> >>   for (ushort i = 0 ; i < 65536 ; ++i){ // Holy King-Kong!
> >>
> >>      for (ushort j = 0 ; j < 65536 ; ++j){
> >>
> >>         status += testStimEq(i,j,cast(ushort)(i+j));
> >>
> >>      }
> >>   }
> >> What is that I am doing ?
> >
> > You have an infinite loop nested within another infinite loop, ushort cannot represent a value which is >= 65536.
> 
> Oops, missed that i & j is 16 bit!. Thanks for pointing that out
> 
> Regards, Sumit

The idea of using correctly sized types everywhere is honorable, but I found that for loops over N iterations better use 32-bit integers or machine word size. One issue is that you cannot iterate over all possible ushorts with a ushort, another is that the loop variables fit better into CPU registers as int/uint or size_t.

So I came to think of loop variables as indexes into the list of ushorts and indexes are size_t. :)

-- 
Marco