String comparisons

Can anyone think of a good way to compare two strings and rate how close they are to each other. For example:
Ericsson Systems

            &
Ericsosn Cystem

You could give these two a rating of 5/16. The 5 indicates that they differ by 5 characters (s & o reversed (2), S & C (2), and missing s (1)) and the 16 is the length of the strings (average=16.5). Received on Mon Dec 29 1997 - 00:00:00 CST