'I have designed a program with more than 500 if elif else' This was your first mistake...
(ii) x3=x1.find(x2) returns an integer corresponding to the start position in x1 where it found x2, otherwise it will return -1. (i) ... what kind of vague numbers? It should just give you an integer response... -- http://mail.python.org/mailman/listinfo/python-list
