How to write UDF in C that resemble the LIKE function

First of all thanks to those who take time to reply to my message.

 

I have a question, as part of the project that I have to do for school, we have to implement a User Define Function in C that is similar like the LIKE funtion in PostgreSQL. For example where a customer is searching for an actor whose last name sounds like "Schwarseneger" (notice the typo). However, the customer is not sure neither about the spelling nor the pronunciation. The real star name should be "Schwarzenegger". In this case, the "LIKE" operator in SQL is not capable enough. It would be nice if the search would match last names "similar to" "Schwarseneger". Can Some one please give me some pointer on this or even sample code that you might have implemented. So basically the thing that I'm doing is like a spell check system where it return the closest match to the word.

 

Thanks in advance

-Brian Trinh