so -----2-----3----5----2----3----- would become -----4-----5----7----4----5-----
if the constant was 2 and etc. for every individual line in the text file.

This would involve splitting recognising numbers in between strings and adding a constant to them e.g ---15--- becomes ---17--- not ---35---.

(basically getting a guitar tab and adding a constant to every fret number)

Thanks. Realised this started out vague and confusing so sorry about that.

lets say the file is:

-2--3--5---7--1/n-6---3--5-1---5

and im adding 2, it should become:

-4--5--7---9--3/n-8---5--7-3---7