Re^2: alternate array elements

With the advent of the new state key word in 5.10. I would think this would be the best solution today.

my @odd  = grep {state $i=1; $i++ % 2}  qw{a 1 b 2 c 3};
my @even = grep {state $i=0; $i++ % 2}  qw{a 1 b 2 c 3};
[download]

Example

perl -e 'use v5.10; my @odd = grep {state $i=1; $i++ % 2}  qw{a 1 b 2 
+c 3}; say @odd;'
[download]

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Re^3: alternate array elements by LanX (Saint) on May 12, 2023 at 21:19 UTC
BTW: for one-liners you can use global vars like `$a` or `$b` without declaration, even when strict. `C:\>perl -e"print grep {++$a % 2} qw{a 1 b 2 c 3}" abc` [download] Though their values will leak into the outer scope, so `state` is better for longer scripts. FWIW: I always thought that an automatic loop-count variable `$c` or `$^c` would come very handy inside grep-like constructs. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]

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Re^3: alternate array elements
by LanX (Saint) on May 12, 2023 at 21:19 UTC

$a

$b

C:\>perl -e"print grep {++$a % 2}  qw{a 1 b 2 c 3}"
abc
[download]

Though their values will leak into the outer scope, so state is better for longer scripts.

FWIW: I always thought that an automatic loop-count variable $c or $^c would come very handy inside grep-like constructs.

Cheers Rolf
_{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)

Wikisyntax for the Monastery}