Pointing someone into the right direction is better than providing the solution without explanation.

seek and tell are working on the filehandle, you could easily work on a variable after reading the line by using "substr" and maybe "length".

But most of the string manipulation in Perl is done using Perl regular expressions. Don't compare them to POSIX, Javascript or other regular expressions, all of them only have a small subset of the Perl RE's power.

\d is a char class for the numbers from 0 to 9, a basic regex for converting your line might be$line =~ s/[^\d]//g;It won't exactly do what you want (cut out too much), but it should be a good start for you. Try to use the Perl regex documentation to understand the expression shown above. Changing them to something really fitting your needs should be easy once you understood the regex.

For gurus: Yes, there is \D, but ^\d is a better learning start for this problem.