To expand on what lhoward pointed out, here's some actual code that you can use (untested):

my %data;
while (<DATA>) {
    ($data{'name'}[$.],
     $data{'address'}[$.],
     $data{'city'}[$.]) 
     = split /,/,$_;
}
[download]

Then, if you want the address from the third record:

print $data{'address'}[3];
[download]

A couple of other points to note:

• $. is a special Perl variable which hold the current line number of the input file. There's no need for $b++ (though some may consider $. to be obfuscated).
• You don't need to escape the comma in your regex.
• Your regex will fail if you have a comma embedded in one of your fields. You should use something like Text::CSV if you do a lot of work with CSV data.

Cheers,
Ovid