This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
somewhere, you're going to have to build all the string you want to compare against. I would consider putting all of them in a set. Then, when you get your new string, you just check to see if it is already in there.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors