Re^2: Only joining elements of an array that are defined

Just a nit,

grep $_, @array

will not include false but defined values:

use strict;
use warnings;

my @array = (1, 2, undef, 4, 5, 0, undef, 8, 9);

print join (' ', grep $_, @array)."\n";
print join (' ', grep { defined } @array)."\n";
[download]

Output

1 2 4 5 8 9
1 2 4 5 0 8 9
[download]

All dogma is stupid.

Comment on Re^2: Only joining elements of an array that are defined Select or Download Code

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Re^3: Only joining elements of an array that are defined by GrandFather (Saint) on Feb 14, 2006 at 10:38 UTC
Argh, I've not been bitten enough by that in real code. I have been bitten enough here by it that I should know better by now! Thanks for clarifying that for OP and the gentle reminder for me. :) DWIM is Perl's answer to Gödel	[reply]
Re^3: Only joining elements of an array that are defined by Anonymous Monk on Feb 14, 2006 at 10:49 UTC
`grep defined, @array`	[reply] [d/l]
Re^4: Only joining elements of an array that are defined by tirwhan (Abbot) on Feb 14, 2006 at 11:11 UTC
<shrug/>Whatever works for you. I find that always using the block form of grep and map is a lot clearer for the compiler as well as human reader, and can prevent mistakes for more complicated expressions, at the cost of one extra character. So unless you're golfing it's probably better to stick with that. All dogma is stupid.	[reply] [d/l]
Re^5: Only joining elements of an array that are defined by Fletch (Bishop) on Feb 14, 2006 at 14:19 UTC
The BLOCK form however does incur a bit more overhead since it has to do all the steps incurred entering and exiting a block. If it's done once, you're probably not going to notice it; if it's a statement you're executing each line for your 1G data file it may add up. Granted it's relatively small and may have been optimized in recent versions, but be aware of the overhead if you're looking for somewhere to shave a few microseconds off after you benchmark (of course always benchmark :).	[reply]
Re^5: Only joining elements of an array that are defined by blazar (Canon) on Feb 15, 2006 at 09:55 UTC
I disagree. If `EXPR` is simple enough, as in this case, then at least for me it is much easier to read. I'm just used to it. Of course should it grow complex enough, then it would soon become a pita, thus I would prefer a `BLOCK` instead. I don't have the slightest idea about the compiler - and I don't care much.	[reply] [d/l] [select]
Re^4: Only joining elements of an array that are defined by Anonymous Monk on Sep 15, 2018 at 09:52 UTC
`grep length,` Is better, because we don't want extra spaces for empty lines	[reply] [d/l]
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