Oh, forgot to say that the strings are pretty large so I don't think arrays would be the best solution.
Each string is about 1 Mbyte that I read in from a file upon request so a standard use is to open about four files (sometimes more, sometimes less) and read values from different indexes in those strings.
I think I tried with a array in the beginning but realized that splitting into 1 Mbyte arrays wasn't fast at all :).