how to delete without resulting in undef

jithoosin has asked for the wisdom of the Perl Monks concerning the following question:

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Re: how to delete without resulting in undef by BrowserUk (Patriarch) on Nov 17, 2005 at 06:27 UTC
You probably want to use splice which removes elements entirely from the array, rather than delete which only deletes their values: `perl> @a = (1 .. 10);; perl> delete $a[ 3 ];; perl> print "@a";; Use of uninitialized value in join or string at 1 2 3 5 6 7 8 9 10 perl> @a = (1 .. 10);; perl> splice @a, 3, 1;; perl> print "@a";; 1 2 3 5 6 7 8 9 10` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal? "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re: how to delete without resulting in undef by Hena (Friar) on Nov 17, 2005 at 06:24 UTC
Command splice is one. It removes the elements completely. `$array[$n]=""` clears it.	[reply] [d/l]
Re: how to delete without resulting in undef by blazar (Canon) on Nov 17, 2005 at 13:07 UTC
As others already pointed out splice is the way to go, since delete only shrinks the array if the element you're deleting is at the end of the array. But the former is more costly. So, depending on you actual code/application, suppose that you may have to eliminate a few elements at a time: you may use the latter and "empty the trash can" later: `delete @array[bad_indices()]; @array = grep defined, @array;` [download] Of course this assumes that you do not want want undefined elements in your array, which seems to be the case, from the description you give.	[reply] [d/l]
Re: how to delete without resulting in undef by jbrugger (Parson) on Nov 17, 2005 at 06:42 UTC
However if you WANT to use 'delete', you allways can do it like this: `#!/usr/bin/perl -w use strict; # updated: Assuming you use strict and warnings :) my @a = (1..10); undef $a[3]; foreach (@a) { print $_ if defined($_); }` [download] "We all agree on the necessity of compromise. We just can't agree on when it's necessary to compromise." - Larry Wall.	[reply] [d/l]