perl: trouble passing array to function

Question

So all i want to do is pass a an array to a function (or subroutine) in PERL

So @Temp contains 2 arrays [0] = {xx,xx,xx,xx,xx} [1] = {xx,xx,xx,xx,xx}

#returns array containing two arrays

my @temp = $lineParser->parseLine($_);

@handOne = $cardFactory->createHand(@Temp[0]);
@handTwo = $cardFactory->createHand(@Temp[1]);

This is the createHand method wich is contained in a seperate class (or package or whatever)

sub createHand
{
    my $self = shift;
    my @temp = @_;
    my @arrayOfCards;
    foreach(@temp)
    {
        my $value = substr($_,0,1);
        my $color = substr($_,1,1);

        push(@arrayOfCards,new Card($value,$color));
    }

    return @arrayOfCards;
}

The problem i am having is that the array gets passed but is contains ARRAY(XXXXX) at the start of the array. E.g. {0 ARRAY(xxxxxx), 0 'xx', 1 'xx', ...}

Why does this happen?

How can I manage to do this correctly?

Is that a typo, or do you have two variables named @temp and @Temp. Because they are two different variables. — TLP
– TLP, Commented May 28, 2013 at 16:00

choroba · Accepted Answer · 2013-05-28 14:59:04Z

4

If you turn on warnings, you will get the following one:

Scalar value @Temp[0] better written as $Temp[0]

If you want to pass the referenced array by value, you have to dereference it:

@handOne = $cardFactory->createHand( @{ $Temp[0] } );

edited May 28, 2013 at 14:59

answered May 28, 2013 at 14:28

choroba

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7 Comments

Ivan Bacher Over a year ago

Thank you, seemed to fix to problem i was having.

Ivan Bacher Over a year ago

WOuld you be able to explain what @{ $Temp[0] } means?

mpapec Over a year ago

Strictly speaking @{ $Temp[0] } doesn't pass an array :)

choroba Over a year ago

@686: $Temp[0] is an array reference. To dereference it, you have to use the dereference operator @{ ... }.

Ivan Bacher Over a year ago

alright cool thx for the reply this is the first thing i have coding in perl =D

|

mpapec · Accepted Answer · 2013-05-28 14:26:25Z

2

sub createHand
{
    my $self = shift;
    my ($temp) = @_;
    my @arrayOfCards;
    foreach(@$temp)
    {
        my $value = substr($_,0,1);
        my $color = substr($_,1,1);

        push(@arrayOfCards,new Card($value,$color));
    }

    return @arrayOfCards;
}

Also take note that @temp[0] is array slice in case where scalar (array ref) is wanted, so it's better to state right intention:

@handOne = $cardFactory->createHand($temp[0]);

answered May 28, 2013 at 14:26

mpapec

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2 Comments

mpapec Over a year ago

You have two options, passing an array or list of values to function. Above example passes an array as you stated in question subject.

Ivan Bacher Over a year ago

@{ $Temp[0] } solved my problem and $Temp[0] doesnt seem to be working

isJustMe · Accepted Answer · 2013-05-28 14:26:00Z

1

You are passing a reference instead of a value.

my @temp = $lineParser->parseLine($_);

@handOne = $cardFactory->createHand($Temp[0]);
@handTwo = $cardFactory->createHand($Temp[1]);

so in a nutshell change @temp[0] to $temp[0] when passing the argument

answered May 28, 2013 at 14:26

isJustMe

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