Jim,
Some time ago a Computer Sci student was working on Linked Lists and
posted some code she needed help with.
> How would such a thing be done with Perl?
Preuse, run, modify and complete this code (it needs a way to remove a
center link, amoung other things.
I don't take credit for this code, it was originally posted as part of a
request for help. I did take this further by extending (in another script)
the ability to link any node to a parent, left child, center child and right
child.
I don't recomend you use this to try to understand C structures (you just
might opt to abandon C altogether ;-) )
#!/usr/bin/perl -w
use strict;
#create list (1)
sub createllist {
my $val = shift;
my $node = shift;
if ( !defined ( $node ) ) {
die 'I need a scalar reference';
}
if ( defined ( $$node ) ) {
die 'You already have a node! ';
}
$$node = {
'data' => $val,
'next' => undef,
};
}
# References V Example Linked List (2)
sub addnode {
my $val = shift;
my $list = shift;
if ( !defined ($list ) ) {
die 'I need a scalar reference';
}
if ( !defined ($$list )) {
print "Creating list \n";
createllist ( $val, $list);
return;
}
if ( defined ($$list -> {'next'} )) {
$list = $$list -> {'next'};
}else {
$$list -> {'next'} = {
'data' => $val,
'next' => undef,
};
return;
}
while ( defined ($list -> {'next'} )) {
$list = $list -> {'next'};
}
$list -> {'next'} = {
'data' => $val,
'next' => undef,
}
}
# To print the values to be used (3)sub printllist {
my $list = shift;
while ( defined ( $list ) ) {
print $list -> {'data'}, "\n";
$list = $list -> {'next'};
}
}
#for debugging, use the Data::Dumper module:
use Data::Dumper;
my $llist;
addnode (1,\$llist );
print "dump:";
print Dumper ($llist);
addnode (2,\$llist );
addnode (3,\$llist );
addnode (4,\$llist );
printllist ( $llist );
print "dump:";
print Dumper ($llist);
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