perls, array, variable length of array

Question

I wish to modify one particular line in perl script :

@list = ([$tmp[0],$tmp[1],$tmp[2]]);

I have change it to this:

if( $input == 3 )
{
        @list = ([$tmp[0],$tmp[1],$tmp[2]]);
}
if( $input == 2 )
{
        @list = ([$tmp[0],$tmp[1]]);
}
if( $input == 1 )
{
        @list = ([$tmp[0]]);
}

Above code works, but I would like it to works with $input values up to 40 .

I try few different approaches but I am not able to code it in more elegant way, which really bother me.

Much appreciated any help with it.

ikegami · Accepted Answer · 2015-07-22 20:47:22Z

6

The following does what you requested:

@list = [ @tmp[ 0 .. $input-1 ] ];

The following does what you want:

my @list = @tmp[ 0 .. $input-1 ];

You can also do the latter in-place very efficiently using the following:

splice(@tmp, $input);

edited Jul 22, 2015 at 20:47

answered Jul 22, 2015 at 20:36

ikegami

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3 Comments

kato sheen Over a year ago

I tested both, what I requested ( as you put it ) is what works in program I modify, thank you.

ikegami Over a year ago

It's using an array to store a single value (a reference to the array that contains the actual values), which is silly.

ikegami Over a year ago

(Unless, you add more to it later)

Hunter McMillen · Accepted Answer · 2015-07-22 20:35:58Z

1

You can use an array slice, which will return a list of elements from the @tmp array that you are interested in:

my @list = @tmp[0..$input-1];

The basic idea is that you copy the elements starting at index 0 to the maximum index you are interested in $input.

answered Jul 22, 2015 at 20:35

Hunter McMillen

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