Classes and Objects Questions and Answers

Q: The structure of C++ programming brings together a group of :

A C++ structure brings together related data items, variables.A struct groups variables that belong together, which may be of different types, under one name: for example a student's roll number (int), name (char array) and marks (float). In C++ a structure can also contain member functions.Items of the same data type are grouped by an array, not a structure, and integers with user-defined names describe an enumeration (enum). Since those two are wrong, 'All of the above' is wrong too.

Q: A static function :

A static function can be called using the class name and function name.A static member function belongs to the class as a whole, not to any particular object. It has no this pointer, can directly access only static members, and is called with the class name and the scope resolution operator, as in Counter::count(), without needing an object.The function called when an object is destroyed is the destructor. A static function needs no dummy object, which is the whole point, and the statement that it is closely connected with an individual object describes ordinary (non-static) member functions.

Q: In C++ .................. operator is used for Dynamic memory allocation.

Dynamic memory is allocated with the new operator.In C++, new allocates memory on the free store (heap) at run time, constructs the object there, and returns a pointer to it; for example int *p = new int[10];. The memory is released with delete or delete[].The scope resolution operator :: names a member or global identifier, the conditional operator ?: chooses between two expressions, and the member access operators (dot and arrow) select a member of an object. None of them allocates memory.

Q: Objects life time generally corresponds to which storage allocation mechanism from the following :(i) Static objects(ii) Stack objects(iii) Heap objects(iv) Serialised objects

The answer is (i), (ii) and (iii).An object's lifetime is tied to how its storage is allocated. Static objects live for the whole run of the program, stack (automatic) objects live from their declaration until their block exits, and heap (dynamic) objects live from explicit allocation until they are freed or garbage collected. These are the three classic storage allocation strategies.Serialisation turns an object into a byte stream for storage or transmission. It is not a storage allocation mechanism, so options naming (iv) are wrong, and (ii) and (iii) alone leaves out static objects.

Q: Which of the following properties makes user defined class good ?(i) Something that has a small and well defined set of operations.(ii) Something that can be seen as a "Black Box" manipulated exclusively through that set of operations.(iii) Something whose actual representation could conceivable be modified without affecting the way that set of operation is used.(iv) Something one might want more than one of.

All four properties make a good class, so the answer is (i), (ii), (iii) and (iv).Stroustrup describes a good user-defined type as something with a small, well-defined set of operations; something that can be treated as a black box, used only through those operations; something whose representation could be changed without changing how the operations are used; and something of which one might want more than one instance.Each of the narrower options leaves out properties from that list.

Q: What happens if delete is used on a pointer not allocated with new in C++ ?

The result is undefined behavior.The C++ standard allows delete only on a pointer obtained from new (or on a null pointer). Applying it to anything else, such as the address of a local variable, memory from malloc or a pointer into the middle of an array, is undefined behaviour: the program may crash, corrupt the heap and fail much later, or appear to work by chance.That is why 'memory is freed safely' and 'program runs normally' are wrong; even if it seems to run, nothing is guaranteed. delete never resets the pointer to NULL by itself, even in the valid case; the programmer must do that.

A/An ______ is a user-defined datatype which has data members and member functions.

A.class
B.object
C.package
D.method

Exam Year(s)

DSSSB TGT - 2023,

Answer: A

A class is a user-defined data type that holds data members and member functions. An object is an instance of a class, created from it, not the type itself. A package is a way of grouping related classes in languages such as Java, and a method is a single function inside a class. Only the class fits the definition. In Java and C++ the keyword class is used to define such a type, and objects are then created from it.

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The structure of C++ programming brings together a group of :

A.Related data items, variables
B.Items of the same data type
C.Integers with user-defined names
D.All of the above

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: A

A C++ structure brings together related data items, variables.

A struct groups variables that belong together, which may be of different types, under one name: for example a student's roll number (int), name (char array) and marks (float). In C++ a structure can also contain member functions.

Items of the same data type are grouped by an array, not a structure, and integers with user-defined names describe an enumeration (enum). Since those two are wrong, 'All of the above' is wrong too.

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A static function :

A.should be called when an object is destroyed
B.can be called using the class name and function name
C.is used when a dummy object must be created
D.is closely connected with and individual object of a class.

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: B

A static function can be called using the class name and function name.

A static member function belongs to the class as a whole, not to any particular object. It has no this pointer, can directly access only static members, and is called with the class name and the scope resolution operator, as in Counter::count(), without needing an object.

The function called when an object is destroyed is the destructor. A static function needs no dummy object, which is the whole point, and the statement that it is closely connected with an individual object describes ordinary (non-static) member functions.

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In C++ .................. operator is used for Dynamic memory allocation.

A.Scope resolution
B.Conditional
C.New
D.Membership access

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: C

Dynamic memory is allocated with the new operator.

In C++, new allocates memory on the free store (heap) at run time, constructs the object there, and returns a pointer to it; for example int *p = new int[10];. The memory is released with delete or delete[].

The scope resolution operator :: names a member or global identifier, the conditional operator ?: chooses between two expressions, and the member access operators (dot and arrow) select a member of an object. None of them allocates memory.

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Objects life time generally corresponds to which storage allocation mechanism from the following :

(i) Static objects
(ii) Stack objects
(iii) Heap objects
(iv) Serialised objects

A.(i), (ii) and (iv)
B.(i), (ii) and (iii)
C.(i), (iii) and (iv)
D.(ii) and (iii)

Exam Year(s)

MH SET - 2020, SET Exam - 2020,

Answer: B

The answer is (i), (ii) and (iii).

An object's lifetime is tied to how its storage is allocated. Static objects live for the whole run of the program, stack (automatic) objects live from their declaration until their block exits, and heap (dynamic) objects live from explicit allocation until they are freed or garbage collected. These are the three classic storage allocation strategies.

Serialisation turns an object into a byte stream for storage or transmission. It is not a storage allocation mechanism, so options naming (iv) are wrong, and (ii) and (iii) alone leaves out static objects.

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Which of the following properties makes user defined class good ?

(i) Something that has a small and well defined set of operations.
(ii) Something that can be seen as a "Black Box" manipulated exclusively through that set of operations.
(iii) Something whose actual representation could conceivable be modified without affecting the way that set of operation is used.
(iv) Something one might want more than one of.

A.(ii) and (iii)
B.(i), (ii), (iii) and (iv)
C.(i) and (ii)
D.(iv) only

Exam Year(s)

MH SET - 2020, SET Exam - 2020,

Answer: B

All four properties make a good class, so the answer is (i), (ii), (iii) and (iv).

Stroustrup describes a good user-defined type as something with a small, well-defined set of operations; something that can be treated as a black box, used only through those operations; something whose representation could be changed without changing how the operations are used; and something of which one might want more than one instance.

Each of the narrower options leaves out properties from that list.

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What is the difference between a "shallow copy" and a "deep copy" in the context of programming languages ?

A.Shallow copy duplicates only references, while deep copy duplicates entire object
B.Shallow copy duplicates entire object, while deep copy duplicates only references
C.Shallow copy duplicates only system variables, whereas deep copy duplicated user defined variables
D.Shallow copy duplicates only user defined variables, whereas deep copy duplicated system variables

Exam Year(s)

MH SET - 2024, SET Exam - 2024,

Answer: A

A shallow copy duplicates only references, while a deep copy duplicates the entire object.

A shallow copy copies the object's fields as they are, so any field that refers to another object still points to the same object; changes through one copy are seen through the other. A deep copy recursively copies the referenced objects too, so the two copies share nothing.

Option B reverses the two. The distinction has nothing to do with system versus user-defined variables, so C and D are wrong.

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What happens if delete is used on a pointer not allocated with new in C++ ?

A.Memory is freed safely
B.Program runs normally
C.Undefined behavior
D.Pointer is reset to NULL

Exam Year(s)

Tripura Public Service Commission - 2026,

Answer: C

The result is undefined behavior.

The C++ standard allows delete only on a pointer obtained from new (or on a null pointer). Applying it to anything else, such as the address of a local variable, memory from malloc or a pointer into the middle of an array, is undefined behaviour: the program may crash, corrupt the heap and fail much later, or appear to work by chance.

That is why 'memory is freed safely' and 'program runs normally' are wrong; even if it seems to run, nothing is guaranteed. delete never resets the pointer to NULL by itself, even in the valid case; the programmer must do that.

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Match the following with respect to C++ data types :

a. User defined type	1. Qualifier
b. Built in type	2. Union
c. Derived type	3. Void
d. Long double	4. Pointer

Code : a b c d

A.2 3 4 1
B.3 1 4 2
C.4 1 2 3
D.3 4 1 2

Exam Year(s)

UGC NET - 2012,

Answer: A

The correct matching is a-2, b-3, c-4, d-1. A union is a user defined type (like struct and class), void is a built-in (fundamental) type, a pointer is a derived type made from other types, and long double is a built-in type with the qualifier long, listed here as the qualifier.

The other codes give Void to the user defined types or the pointer to the built-in type, which is wrong. So the code 2 3 4 1 is the answer.

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10.

Important advantage of using new and delete operators in C++ is

A.Allocation of memory
B.Frees the memory previously allocated
C.Initialization of memory easily
D.Allocation of memory and frees the memory previously allocated.

Exam Year(s)

UGC NET - 2013,

Answer: D

The advantage of new and delete is both allocation of memory and freeing of memory previously allocated, and in addition new can initialize the object. Option D combines the two functions new (allocate) and delete (free), which are the key purpose of the operators.

Options A and B each name only half of the pair, so they are incomplete. Option C names a possible benefit, initialization, but not the main function pair described in D.

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