What are custom exceptions??

Answer 1

@gowri why you always post a thread then explain answer yourself?

Answer 2

C doesn't have exceptions, unless you implement them. In which case, they would all be custom.

Answer 3

in c++ you can inherit from exception class and you can overwrite the virtual method "what" (write your own information about the exception"), the when an exception is catched by try catch sentence, the information of the exception can be obtained by call the method what.
www.cplusplus.com/doc/tutorial/exception/
topic: standard exceptions