UPDATED: Having been censured for answering an easy question, I'll try going all Perlmonks.

my $FOUR_DIGIT_CAPTURE 
    = qr/
        ( 
          # left as an exercise
        )
        /x;
while (<DATA>) {
    if (my ($four_digit_num) = /$FOUR_DIGIT_CAPTURE/) {
        print # left as an exercise
    }
    else {
        # left as an exercise
    }
}
__DATA__
j9999120.125
Be sure to include lots of interesting test cases.

[download]

In reply to Re: How to extract the 4 number in the filename? by Narveson
in thread How to extract the 4 number in the filename? by padawan_linuxero

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