C++ Acessing Virtual Functions of Custom Exception Class from Catch Statement

[Nabhi18]

I am now working on an idea to create a single catch statement and identify the validation and some run time exceptions. So I did create two custom exception classes with the virtual function for what(). The problem is that I am getting std::exception when I tried to access the virtual function.

Whenever there is an exception that occurs, I created a pointer object for the base class and an object for the custom execption class and i assigned the reference of the custom exception class object to the base class pointer and I did throw the base class pointer and tried to access it from the catch statement but I am getting std::exception as output! Help me out where I am wrong.

This is my Header File

#include<iostream>
#include<exception>
using namespace std;
class A
{
protected:
int a,b;
public:
bool setdata();
virtual void calculate()=0;
};

class B : public A
{
virtual void  calculate();
};

class DivideException : public exception{
public:
virtual const char * what() const throw()
{
return "It is a divide by zero exception\n";
}
};

class InputException : public exception{
public:
virtual const char * what() const throw()
{
return "It is an Input Exception";
}
};

This is my Implementation .cpp File

#include"head.h"
#include<string>
#include"sstream"
void B :: calculate()
{
try{
cin>>a;
if(!cin)
{
exception *i;                        //The Way I tried to access the Virtual Function
InputException f;
i=&f;
throw i;
}
cin>>b;
if(!cin)
{
exception *i;
InputException f;
i=&f;
throw i;
}
if (b == 0)
{
exception *j;
DivideException  d;
j=&d;
throw j;
}
else
{
cout << "a / b = " << a/b << endl;
}
}
catch( std::exception* e)
{
cout<<(e->what()); //No matter what Exception I throw, it keeps printing me std::exception
}
}

Here is my main.cpp file, it is quite simple.

#include"head.h"
int main()
{
A *obj;
B e;
obj=&e;
obj->calculate();
return 0;
}

What am I doing wrong here????? Sample I/O:

1 0 std::exception

1 a std::exception

Output I am expecting: 1 0 It is a Divide by Zero Exception.

1 a It is a Input Exception