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Re: can we pass two variable to foreach loop

by grinder (Bishop)
on Mar 28, 2007 at 06:36 UTC ( #606919=note: print w/replies, xml ) Need Help??

in reply to can we pass two variable to foreach loop

Taking n elements of an array at a time is about the only truly useful purpose to which a C-style for loop in Perl may be put. That said, beware of the last iteration of the loop. If the number of elements in the list divided by the number taken each turn leaves a remainder, the last iteration will come up short and you'll have to test whether the element pointed to by the index is defined or not. For instance 5 elements taken 2 at a time gives 1 element left over in the last time through the loop.

On the other hand, if you don't mind emptying out the array by removing the n elements at a time, then splice will work as well, and as an added bonus, if the final iteration comes up short, splice will simply return fewer elements. If you use them as an array you're fine. Then again, if you need to distinguish them individually, you'll have to test how many splice gave you.

use strict; use warnings; my @arr = ('a' .. 'z', 'Z'); # non-destructively for (my $i = 0; $i < @arr; $i += 2) { print "$arr[$i] $arr[$i+1]\n"; } # destructively while (my @pair = splice(@arr, 0, 2)) { print "@pair\n"; }

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