One-liner: 
perl -e \
'$_="A3xyz45M98AB7Z9",s/(\d)([a-zA-Z])/$1:$2/gsi,print'

[download]
Using split: 
use strict;

my $s = "A3xyz45M98AB7Z9";
my @stuff = split(//,$s);
for (my $j=0;$j<@stuff;$j++) {
  if ($stuff[$j] =~ /\d/ && $stuff[$j+1] && $stuff[$j+1] =~ /[a-zA-Z]/
+) {
    print "$stuff[$j]:";
  } else {
    print "$stuff[$j]";
  }
}

[download]

I'm working on a way to make it as complicated as possible. Just because.

piroufreek

In reply to Re: Best way to put : between fields in a string by piroufreek
in thread Best way to put : between fields in a string by eyepopslikeamosquito

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