Removal of "NULL" element in an array?

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

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Re: Removal of "NULL" element in an array? by Paladin (Vicar) on Jan 07, 2003 at 23:56 UTC
`splice()` `pop()` and `shift()` are good if you know where the elements you want to remove are. If you want to remove all undefined elements you could use `grep` `@foo = grep {defined} @foo; # Only return elements that are defined` You can replace `defined` with some other test if your definition of NULL is not definedness.	[reply] [d/l] [select]
Re: Removal of "NULL" element in an array? by submersible_toaster (Chaplain) on Jan 07, 2003 at 23:47 UTC
If the null element is the last in the array then you can `pop @array` Or as your example states, at the beginning of the array, `shift @array` However for anything trickier , like removing the null at `$array[45]` , you want to investigate splice Regarding chomp, chomp will only remove a newline char from a string (or array of strings). I can't believe it's not psellchecked	[reply] [d/l] [select]
Re: Re: Removal of "NULL" element in an array? by bart (Canon) on Jan 07, 2003 at 23:56 UTC
However for anything trickier , like removing the null at $array[45] , you want to investigate splice or grep. `@a = grep { $_ ne '' } @data;` [download]	[reply] [d/l]
Re: Removal of "NULL" element in an array? by cchampion (Curate) on Jan 08, 2003 at 12:26 UTC
By "NULL," do you mean only undefined items or also the empty ones? If you want to exclude only the items that are not defined, then use `my @clean = grep { defined } @data;` [download] If you want to skip the empty items, then use `my @clean = grep { $_ ne '' } @data;` [download] However, the above code will break on undefined items. If you want to combine both approaches, then the "right" approach is: `#!/usr/bin/perl -w use strict; my @data= (1, 2, 3, 'a', undef, 4, '', 5, 'b'); my @clean = grep { defined && $_ ne '' } @data; print join ",", @clean; print "\n";` [download] output: 1,2,3,a,4,5,b HTH cchampion	[reply] [d/l] [select]