86. Identify the correct statement.

1. 1. typedef create own types

   
   
   

   2. typedef does not create different types. It only creates synonyms of existing types

   
   
   

   3. typedef create different types

   
   
   

   4. All of above

   
   
   

   5. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   By using typedef, we can create a type of pre-existing type only not our own type of data.

---

87. What does the data type defined by union will do?

1. 1. It allow one same portion of memory to be accessed as different data types

   
   
   

   2. It allow one different portion of memory to be accessed as different data types

   
   
   

   3. It allow one different portion of memory to be accessed as same data types

   
   
   

   4. It allow one same portion of memory to be accessed as same data types

   
   
   

   5. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   Union is used to define the data types of our choice and it will store the data type in one location make them accessible.

---

---

88. What is the output of this program?
    

    #include <iostream>
        #include <exception>
        using namespace std;
        class BaseClass 
        { 
            virtual void dummy() {} 
        };
        class DerivedClass: public BaseClass 
        { 
            int num; 
        };
        int main () 
        {
            try 
            {
                BaseClass * ptr1 = new DerivedClass;
                BaseClass * ptr2 = new BaseClass;
                DerivedClass * ptr3;
                ptr3 = dynamic_cast(ptr1);
                if (ptr3 == 0) 
                    cout << "Null pointer on first type-cast" << endl;
                ptr3 = dynamic_cast(ptr2);
                if (ptr3 == 0) 
                    cout << "Null pointer on second type-cast" << endl;
            } 
            catch (exception& excep) 
            {
                cout << "Exception: " << excep.what();
            }
            return 0;
        }
    

1. 1. Null pointer on first type-cast

   
   
   

   2. Null pointer on second type-cast

   
   
   

   3. Exception:

   
   
   

   4. All of above

   
   
   

   5. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   In this program, We apply the dynamic cast to ptr3. Based on the value in the ptr3, it produces the output.

---

89. To which type of class, We can apply RTTI?

1. 1. Polymorphic

   
   
   

   2. Derived

   
   
   

   3. Encapsulation

   
   
   

   4. All of above

   
   
   

   5. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   RTTI is available only for classes which are polymorphic, which means they have at least one virtual method.

---

---

90. Which operators are part of RTTI?

1. 1. function

   
   
   

   2. dynamic_cast()

   
   
   

   3. typeid

   
   
   

   4. both dynamic_cast() & typeid

   
   
   

   5. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   The dynamic_cast<> operation and typeid operator in C++ are part of RTTI.

---