How to modify array elements using subroutine in perl

Question

I am trying to modify the array passed to subroutine. I am passing the reference to the subroutine and assigning new values but it is not getting reflected in the caller side.
Below is my program.

sub receiveArray {

        my $arrayref = @_;

        @{$arrayref} = (4, 5, 6);

}



@ar = (1, 2,3 );

print "Values of the function before calling the function\n";

foreach my $var (@ar) {

        print $var;

        print "\n";

}

receiveArray(\@ar);

print "Values of the function after calling the function\n";

foreach my $var (@ar) {

        print $var;

        print "\n";

}

What is the problem in the above code. Any help would be greatly appreciated. Thanks in advance

Answer 1

You should start every Perl file you write with use strict; use warnings;. That will help you avoid errors like this.

The problem is in this line:

    my $arrayref = @_;

You're assigning an array to a scalar, so the array is evaluated in scalar context, which yields the number of elements in the array.

What you should do instead is:

    my ($arrayref) = @_;

Now it's using list assignment, putting the first function argument into $arrayref (and ignoring the rest, if any).

List assignment is documented in perldoc perldata (the part starting with "Lists may be assigned to ...").

How to modify array elements using subroutine in perl

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