CODEWITHSUNDEEP
arraysperl
thkala
thkala

Reputation: 86353

How to get all elements from index N to the end from an anonymous Perl array?

In Perl 5, when we have a named array, e.g. @a, getting the elements from index $N onwards is simple with a bit of slicing:

my @result = @a[$N..$#a];

Is there a standard way to do the same with an anonymous array, without having to supply the length explicitly? I.e. can this:

my @result = (0,1,2,3,4,5)[2..5];

or, more specifically, this:

my @result = (0,1,2,3,4,5)[$N..5];

be converted to something that does not need the upper range limit to be explicit? Perhaps some obscure Perl syntax? Maybe a bit of dicing instead of slicing?

PS: I have already written this as a function - I am looking for a more self-contained approach.

Upvotes: 15

Views: 12735

Answers (4)

Galo Ainstein
Galo Ainstein

Reputation: 1

I just use the array variable to get the len:

@a = (1,2,3,4,5);
print @a[1..@a];
# output: (2,3,4,5)

Upvotes: -1

mwp
mwp

Reputation: 8467

I think mob's splice is the best option, but in the spirit of options:

my @result = reverse ((reverse 0..5)[0..$N+1]);

This returns the same result as the above example:

my @result = (0..5)[$N..5];

Upvotes: 2

Eric Strom
Eric Strom

Reputation: 40152

You don't need to give an array ref a name if you set it as the topic:

    sub returns_array_ref {[1 .. 5]}

    my @slice = map @$_[$n .. $#$_] => returns_array_ref;

Or if you are working with a list:

    sub returns_list {1 .. 5}

    my @slice = sub {@_[$n .. $#_]}->(returns_list);

Upvotes: 1

mob
mob

Reputation: 118615

You can splice it:

@result = splice @{[0..$M]}, $N;  # return $N .. $M

Upvotes: 21

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