61 practice sets · Page 3 of 4
While returning an object, we can use ____________
Copy constructor
Default constructor
Parameterized constructor
Zero argument constructor
Correct Answer: A — Copy constructor
Explanation:
While returning an object we can use the copy constructor. When we assign the return value to another object of same class then this copy constructor will be used. And all the members will be assigned the same values as that of the object being returned.
The copy constructors can be used to ________
Copy an object for type casting
Copy an object so that it can be passed to a function
Copy an object so that it can be passed to a class
Copy an object so that it can be passed to another primitive type variable
Correct Answer: B — Copy an object so that it can be passed to a function
Explanation:
When an object is passed to a function, actually its copy is made in the function. To copy the values, copy constructor is used. Hence the object being passed and object being used in function are different.
If two classes have exactly same data members and member function and only they differ by class name. Can copy constructor be used to initialize one class object with another class object?
No, but possible if constructor is also same
Yes, because the members are same
No, not possible
Yes, possible
Correct Answer: C — No, not possible
Explanation:
The restriction for copy constructor is that it must be used with the object of same class. Even if the classes are exactly same the constructor won’t be able to access all the members of another class. Hence we can’t use object of another class for initialization.
The copy constructor can be used to ____________
Initialize one object from another object of same type
Initialize all the objects of a class to another object of another class
Initialize one object from another object of different type
Initialize more than one object from another object of same type at a time
Correct Answer: A — Initialize one object from another object of same type
Explanation:
The copy constructor has the most basic function to initialize the members of an object with same values as that of some previously created object. The object must be of same class.
Copy constructor is a constructor which ________________
Creates an object by copying values from another object of another class
Creates an object by copying values from first object created for that class
Creates an object by initializing it with another previously created object of same class
Creates an object by copying values from any other object of same class
Correct Answer: C — Creates an object by initializing it with another previously created object of same class
Explanation:
The object that has to be copied to new object must be previously created. The new object gets initialized with the same values as that of the object mentioned for being copied. The exact copy is made with values.
References to object are same as pointers of object.
False
True
Correct Answer: A — False
Explanation:
The references are made to object when the object is created and initialized with another object without calling any constructor. But the object pointer must be declared explicitly using symbol that will be capable of storing some address. Hence both are different.
What should be done to prevent changes that may be made to the values pointed by the pointer?
Pointer should be made const
Pointer should be made anonymous
Usual pointer can’t change the values pointed
Pointer should be made virtual
Correct Answer: A — Pointer should be made const
Explanation:
The pointer should be declared as a const type. This prevents the pointer to change any value that is being pointed from it. This is a feature that is made to access the values using pointer but to make sure that pointer doesn’t change those values accidently.
How can the address stored in the pointer be retrieved?
Using * symbol
Using @ symbol
Using $ symbol
Using & symbol
Correct Answer: D — Using & symbol
Explanation:
The & symbol must be used. This should be done such that the object should be preceded by & symbol and then the address should be stored in another variable. This is done to get the address where the object is stored.
If a pointer to an object is created and the object gets deleted without using the pointer then __________
It becomes void pointer
It becomes dangling pointer
It becomes zero pointer
It becomes null pointer
Correct Answer: B — It becomes dangling pointer
Explanation:
When the address pointed by the object pointer gets deleted, the pointer now points to an invalid address. Hence it becomes a dangling pointer. It can’t be null or void pointer since it doesn’t point to any specific location.
Which is the correct syntax to call a member function using pointer?
pointer::function()
pointer.function()
pointer->function()
pointer:function()
Correct Answer: C — pointer->function()
Explanation:
The pointer should be mentioned followed by the arrow operator. Arrow operator is applicable only with the pointers. Then the function name should be mentioned that is to be called.
Which among the following is true?
The pointer can’t hold any value
The pointer can hold value of any type
The pointer to object can hold address only
The pointer can hold only void reference
Correct Answer: C — The pointer to object can hold address only
Explanation:
The pointer to an object can hold only the addresses. Address of any other object of same class. This allows the programmer to link more than one objects if required.
Is name of an array of objects is also a pointer to object?
No, because it represents more than one object
Yes, always
No, never
Yes, in few cases
Correct Answer: B — Yes, always
Explanation:
The array name represents a pointer to the object. The name alone can represent the starting address of the array. But that also represents an array which is in turn stored in a pointer.
Can pointers to object access the private members of the class?
Yes, always
Yes, only if it is only pointer to object
No, never
No, because objects can be referenced from another objects too
Correct Answer: C — No, never
Explanation:
The pointers to an object can never access the private members of the class outside the class. The object can indirectly use those private members using member functions which are public in the class.
Pointer to a base class can be initialized with the address of derived class, because of _________
base-to-base implicit conversion for pointers
derived-to-derived implicit conversion for pointers
derived-to-base implicit conversion for pointers
base-to-derived implicit conversion for pointers
Correct Answer: C — derived-to-base implicit conversion for pointers
Explanation:
It is an implicit rule defined in most of the programming languages. It permits the programmer to declare a pointer to the derived class from a base class pointer. In this way the programmer doesn’t have to declare object for derived class each time it is required.
A pointer _________________
Can point to only 2 objects at a time
Can point to more than one objects at a time
Can point to whole class objects at a time
Can point to only one object at a time
Correct Answer: D — Can point to only one object at a time
Explanation:
The object pointer can point to only one object at a time. The pointer will be able to store only one address at a time. Hence only one object can be referred.
What is the size of an object pointer?
Equal to size of maximum sized member of object
Equal to size of any usual pointer
Equal to size of void
Equal to size of sum of all the members of object
Correct Answer: B — Equal to size of any usual pointer
Explanation:
The size of object pointer is same as that of any usual pointer. This is because only the address have to be stored. There are no values to be stored in the pointer.
If pointer to an object is declared __________
It can only store address of integer type
It can store only void addresses
It can store any type of address
It can only store object address of class type specified
Correct Answer: D — It can only store object address of class type specified
Explanation:
The address of only the specified class type can get their address stored in the object pointer. The addresses doesn’t differ but they do differ for the amount and type of memory required for objects of different classes. Hence same class object pointer should be used.
How does compiler decide the intended object to be used, if more than one object are used?
Using void pointer
Using this pointer
Using object name
Using an integer pointer
Correct Answer: B — Using this pointer
Explanation:
This pointer denotes the object, in which it is being used. If member function is called with respect to one object then this pointer refers to the same object members. It can be used when members with same name are involved.
Which operator should be used to access the members of the class using object pointer?
Arrow operator
Scope resolution operator
Colon to the member
Dot operator
Correct Answer: A — Arrow operator
Explanation:
The members can be accessed from the object pointer by using arrow operator. The arrow operator can be used only with the pointer of class type. If simple object is declared, it must use dot operator to access the members.
Which is correct syntax for declaring pointer to object?
className objectName();
className* objectName;
*className objectName;
className objectName;
Correct Answer: B — className* objectName;
Explanation:
The syntax must contain symbol after the className as the type of object. This declares an object pointer. This can store address of any object of the specified class.
