Question

I have a bunch of strings like this:

my $string1 = "xg0000";
my $string2 = "fx0015";

What do I do to increase the number in the string by 1 but also maintain the leading zeros to keep the length of the string the same.

I tried this:

$string =~ s/(\d+)/0 x length(int($1)) . ($1+1)/e;

It doesn’t seem to work on all numbers. Is regex what I’m supposet to use to do this or is there a better way?

Answer 1

How about a little perl magic? The ++ operator will work even on strings, and 0000 will magically turn into 0001.

Now, we can’t modify $1 since it is readonly, but we can use an intermediate variable.

use strict;
use warnings;
my $string = "xg0000"; 
$string =~ s/(\d+)/my $x=$1; ++$x/e; 

Update:

I didn’t think of this before, but it actually works without a regex:

C:\perl>perl -we "$str = 'xg0000'; print ++$str;"
xg0001

Still does not solve the problem DavidO pointed out, with 9999. You would have to decide what to do with those numbers. Perl has a rather interesting solution for it:

C:\perl>perl -we "$str = 'xg9999'; print ++$str;"
xh0000