how to create own exception and what is pure virtual function.

Question

I got the question on create own exeption for the array having size less than 0 .

Answer 1

You can use the error types available in stdexcept to create your own execption messages.

Eg :

int arr[5];
int index; cin>>index;
if(index>5||index<0)
throw out_of_range("Index is out of bounds!");

Now, you can catch your exception by putting the above code in a try block and declaring a catch block below it like this :

catch(exception& e)
{ cerr<<e.what(); }

Note that I did not use the size example as arrays use sizes in unsigned form and thus int arr[-1] will become int arr[4294967295].

For knowing about pure virtual functions, you can visit :

www.cplusplus.com/doc/tutorial/polymorphism

https://www.sololearn.com/learn/CPlusPlus/1912/