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From: Glenn Schrader <gschrad@ll.mit.edu>
Subject: Re: Multiple declarations in for loop?
Date: 1998/05/29
Message-ID: <356B0149.83BE3151@ll.mit.edu>#1/1
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Approved: Fergus Henderson <fjh@cs.mu.oz.au>
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James Kuyper wrote:
<snip> 
> > It would be odd, but I think it would be worth it, because
> > it is frequently needed, and the alternatives are pretty
> > ugly. If the goal is to reduce oddity, maybe allowing
> > it in all other relevant contexts would be a solution :-) ?
> > Unless it would break something else, of course.
> 
> I don't think that the following is very ugly, just a little clumsy:
> 
> {
>         unsigned int j;
>         for(int i=0; i<10 && /* Note correction */ j<10; i++, j++)
>         {
>                 // Loop body; which presumably changes i or j, but not
>                 // always in the same way; otherwise j is redundant.
>         }
> }

How about the following? The basic idea is to use an object (in this
case defined as a struct) to aggregate the separate loop variables.


#include <iostream.h>

int
main(void)
{
  for(struct {int i; unsigned j;} loopvar = { -3, 0 };
      loopvar.j < 10;
      ++loopvar.i, ++loopvar.j)
    {
      cout << "i = " << loopvar.i 
           << ", j = " << loopvar.j << endl;
    }
  return 0;
}


-- 
 ============================================================
 | Glenn Schrader         | Email gschrad@ll.mit.edu        |
 ============================================================
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