CMPH - C Minimal Perfect Hashing Library

Coincidentally, following yesterday's entry about the state of computer science education, I came across an excellent Sourceforge project CMPH (C Minimal Perfect Hashing Library). It's not too bad to use - it's written in C but unusually for open source projects, it includes a considerable amount of theory at a level I'd guess of second or third year undergraduate.

Hash functions are used everywhere in desktop and server applications to transform an identifying element of data, typically a key, into a small number that can be used to index that data. Doing this well depends on the type and size of the data. The CMPH library offers four algorithms which between them can use small memory or work very fast or handle hundreds of millions of items of data. Good luck understanding all the maths! I've added a link this into the C Library.

• Link to C Code Library