There was a discussion about this once before and it seemed a lot of people were interested in it. I wish I could find it. I do remember that nobody here came up with an effective way of doing what you're asking.

One of the problems is that a text string may have more than one combination of words. I suppose things would be made easier if the words to find in the string came from a very limited dictionary.

Anyhow, I hope somebody else chimes in..

Which is also using a dictionary.
No mater how you look at tackling this in any coding language it is going to require a dictionary of words to match against. And even then you would probably need an algorithm for checking against another list of common multiples that would be used together in a string.