Is there any difference in error and no output ?

Answer 1

of course. there are functions without error or output. but when you expect an output and there is none, it's because of an error.

Answer 2

yaa if u have logical error then u may get wrong output.sometimes ur program don't have any error.but it may not have any output since u want to check whether its syntax error free or not.so these are 2 different things.