how to slice am array ref and return an array ref in one line?

Question

Consider the following lines of code. I want to slice the array ref $a and return the result as an array ref assigned to $b. I can do that in two lines as shown. I am stumped in my attempts to do this in one line! How can this be done?

$a = [1,2,3,4,5];
###the desired result###########################
@b = @{$a}[1 .. @{$a} - 1];
$b = \@b; # $b is [2,3,4,5]
################################################
###trying to get the desired result in one line##
$b = \@{$a}[1 .. @{$a} - 1]; # $b is \5;
$b = \{@{$a}[1 .. @{$a} - 1]}; # $b is \{ 2 => 3, 4 => 5 }
$b = $a->[1 .. @{$a} - 1]; # $b is 1
$b = $a->@[1 .. @{$a} - 1]; # $b is 5

Side note: avoid using $a and $b specifically even as examples, as they are special globals for the sort function - it either bypasses the typo-checking benefits of strict 'vars', or if you declare them lexically, breaks sort calls in that scope. I suggest $x/$y — Grinnz
– Grinnz, Commented Apr 15, 2019 at 23:21
The reason why your attempts are not valid ways to create a reference are because you cannot reference a slice of an array, you must reference a full array. Thus you must create a new array reference, with copies of the sliced elements, as shown in the answers. — Grinnz
– Grinnz, Commented Apr 15, 2019 at 23:24
Also, if you want to modify the array in place rather than create a new one, the splice function may be useful (it also works on dereferenced arrayrefs). Just take care that this is really what you want. — Grinnz
– Grinnz, Commented Apr 15, 2019 at 23:43

ikegami · Accepted Answer · 2019-04-16 09:13:17Z

4

you can say

$b = [ @{$a}[1 .. @{$a} - 1] ];

edited Apr 16, 2019 at 9:13

ikegami

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answered Apr 15, 2019 at 23:00

Michael Quaranta

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mob · Accepted Answer · 2019-04-15 23:50:05Z

2

Inspired by this question, there is also

$b = [ splice @{[@$a]},1 ]

answered Apr 15, 2019 at 23:50

mob

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1 Comment

Grinnz Over a year ago

splice @{$b = [@$a]}, 0, 1 would create only one copy, as the other solutions do.

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