Your answer is not quite right. test with this:

$a = "12||23||34||45";

@a = split("\|\|", $a);
print join(",", @a);
[download]

Instead of giving you,

12,23,34,45
[download]

It gives you

1,2,|,|,2,3,|,|,3,4,|,|,4,5
[download]

You have to say:

$a = "12||23||34||45";

@a = split(/\|\|/, $a);
print join(",", @a);
[download]

Or, if you want to use quots, say:

$a = "12||23||34||45";

@a = split("\\|\\|", $a);
print join(",", @a);
[download]

The reason is simple:

1. For that "|", you need to escape it within regexp, but not within quots.
2. For that "\", you have to escape it within quots.

So if you say "\\|",

1. First it is being intepreted by the quots as "\|",
2. Then it is being further interpreted by the regexp as "|".