This is a FAQ. For multiple good ideas how to do this (including code) once you've loaded your data into an array, see How can I remove duplicate elements from a list or array?

In your post, you specifically request I need to be able to capture each unique string and assign it to a variable. Is there a specific and compelling reason to use an initially unknown number of scalars as opposed to an array or hash? You could do it with Symbolic references, but those will generally cause more headaches than they will solve. In fact, using them in this kind of case is generally considered a classic example of poor form.