> how can i call c function from jsp?
Use JNI. Make a Java interface for the C function, and call it in JSP.
> please explain me in detail.
Unless you're going to pay me for my service ;)
this link is all I can give you:
http://java.sun.com/docs/books/tutorial/native1.1/index.html,
especially
http://java.sun.com/docs/books/tutorial/native1.1/implementing/index.html