David Gilden wrote:
> Hello,
>
> I am building a primary key for a database, and I guess the first
> question would be
> how safe is a key made from the last 4 digits of a social security
> num and the first 3 letters of the last name. Now for the PERL
> question, I have substr. line working correctly. I wanted to try it
> with ReGrex, but the syntax is escaping me.
> Any pointers would appreciated!
> Thanks,
> Dave
> ( webmaster @ www.coraconnection.com / Ft. Worth, TX, USA)
>
>
> #!/usr/bin/perl -w
> #use strict;
>
> $ss = '1234567890';
> $lname = 'Gilden';
> # $pkey = substr($ss,length($ss)-4,length($ss)) . substr($lname,0,3); This
> substr does what you want but only because of the size of the data. If you had a
> larger field, you would get more digits as part of your key. What you are getting
> for your substr is a length of 10 to pull, but you really only want 4 digits.
> # print "$pkey\n";
>
> $ss = '09876543';
> $lname = 'Smith';
> # this line is bad! -- trying to have the same functionality as the
> substr line. $pkey = ($ss =~ m/\d{length($ss)-4}($ss{length($ss)})/);
f you want the last four digits of the field, then /(\d{4})$/ will get the
last four digits you want.
> # $pkey = ($pkey =~ m/$lname{0,3}/;)
> print "$pkey\n";
>
> # Is there any advantage using =~ m/(\w){3}/ over substr method?
substr will be faster so if doing a lot and have control over the input, then
the substr would be the way to go.
Wags ;)
>
> __END__
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