Comparison of multi-part alphanumeric strings

Comparison of multi-part alphanumeric strings

I receive a string which contains the sw version currently running in the
system.
I want to do some operations only if the system is running on a certain sw
version or later.
e.g. If system is running sw version 2.D or later (2.E, ..) I do some
operations. If system is running lower sw version (2.C, ..) I do not do
it.
How to do this comparison for strings?