Object Oriented MCQ Set 1
1. Which was the first purely object oriented programming language developed?
a) Java
b) C++
c) SmallTalk
d) Kotlin
Answer
Answer: c [Reason:] SmallTalk was the first programming language developed which was purely object oriented. It was developed by Alan Kay. OOP concept came into picture in 1970’s.
2. Which of the following best defines a class?
a) Parent of an object
b) Instance of an object
c) Blueprint of an object
d) Scope of an object
Answer
Answer: b [Reason:] A class is Blueprint of an object which describes/ shows all the functions and data that are provided by an object of a specific class. It can’t be called as parent or instance of an object. Class in general describes all the properties of an object.
3. Who invented OOP?
a) Alan Kay
b) Andrea Ferro
c) Dennis Ritchie
d) Adele Goldberg
Answer
Answer: a [Reason:] Alan Kay invented OOP, Andrea Ferro was a part of SmallTalk Development. Dennis invented C++ and Adele Goldberg was in team to develop SmallTalk but Alan actually had got rewarded for OOP.
4. What is the additional feature in classes that was not in structures?
a) Data members
b) Member functions
c) Static data allowed
d) Public access specifier
Answer
Answer: b [Reason:] Member functions are allowed inside a class but were not present in structure concept. Data members, static data and public access specifiers were present in structures too.
5. Which is not feature of OOP in general definitions?
a) Code reusability
b) Modularity
c) Duplicate/Redundant data
d) Efficient Code
Answer
Answer: c [Reason:] Duplicate/Redundant data is dependent on programmer and hence can’t be guaranteed by OOP. Code reusability is done using inheritance. Modularity is supported by using different code files and classes. Codes are more efficient because of features of OOP.
6. Pure OOP can be implemented without using class in a program. (True or False)
a) True
b) False
Answer
Answer: b [Reason:] It’s false because for a program to be pure OO, everything must be written inside classes. If this rule is violated, the program can’t be labelled as purely OO.
7. Which Feature of OOP illustrated the code reusability?
a) Polymorphism
b) Abstraction
c) Encapsulation
d) Inheritance
Answer
Answer: d [Reason:] Using inheritance we can reuse the code already written and also can avoid creation of many new functions or variables, as that can be done one time and be reused, using classes.
8. Which language does not support all 4 types of inheritance?
a) C++
b) Java
c) Kotlin
d) Small Talk
Answer
Answer: b [Reason:] Java doesn’t support all 4 types of inheritance. It doesn’t support multiple inheritance. But the multiple inheritance can be implemented using interfaces in Java.
9. How many classes can be defined in a single program?
a) Only 1
b) Only 100
c) Only 999
d) As many as you want
Answer
Answer: d [Reason:] Any number of classes can be defined inside a program, provided that their names are different. In java, if public class is present then it must have the same name as that of file.
10. When OOP concept did first came into picture?
a) 1970’s
b) 1980’s
c) 1993
d) 1995
Answer
Answer: a [Reason:] OOP first came into picture in 1970’s by Alan and his team. Later it was used by some programming languages and got implemented successfully, SmallTalk was first language to use pure OOP and followed all rules strictly.
11. Why Java is Partially OOP language?
a) It supports usual declaration of primitive data types
b) It doesn’t support all types of inheritance
c) It allows code to be written outside classes
d) It does not support pointers
Answer
Answer: a [Reason:] As Java supports usual declaration of data variables, it is partial implementation of OOP. Because according to rules of OOP, object constructors must be used, even for declaration of variables.
12. Which concept of OOP is false for C++?
a) Code can be written without using classes
b) Code must contain at least one class
c) A class must have member functions
d) At least one object should be declared in code
Answer
Answer: b [Reason:] In C++, it’s not necessary to use classes, and hence codes can be written without using OOP concept. Classes may or may not contain member functions, so it’s not a necessary condition in C++. And, an object can only be declared in a code if its class is defined/included via header file.
13. Which header file is required in C++ to use OOP?
a) iostream.h
b) stdio.h
c) stdlib.h
d) OOP can be used without using any header file
Answer
Answer: d [Reason:] We need not include any specific header file to use OOP concept in C++, only specific functions used in code need their respective header files to be included or classes should be defined if needed.
14. Which of the two features match each other?
a) Inheritance and Encapsulation
b) Encapsulation and Polymorphism
c) Encapsulation and Abstraction
d) Abstraction and Polymorphism
Answer
Answer: c [Reason:] Encapsulation and Abstraction are similar features. Encapsulation is actually binding all the properties in a single class or we can say hiding all the features of object inside a class. And Abstraction is hiding unwanted data (for user) and showing only the data required by the user of program.
15. Which feature allows open recursion, among the following?
a) Use of this pointer
b) Use of pointers
c) Use of pass by value
d) Use of parameterized constructor
Answer
Answer: a [Reason:] Use of this pointer allows an object to call data and methods of itself whenever needed. This helps us call the members of an object recursively, and differentiate the variables of different scopes.
Object Oriented MCQ Set 2
1. Which feature of OOP indicates code reusability?
a) Encapsulation
b) Inheritance
c) Abstraction
d) Polymorphism
Answer
Answer: b [Reason:] Inheritance indicates the code reusability. Encapsulation and abstraction are meant to hide/group data into one element. Polymorphism is to indicate different tasks performed by a single entity.
2. If a function can perform more than 1 type of tasks, where the function name remains same, which feature of OOP is used here?
a) Encapsulation
b) Inheritance
c) Polymorphism
d) Abstraction
Answer
Answer: c [Reason:] For the feature given above, the OOP feature used is Polymorphism. Example of polymorphism in real life is a kid, who can be a student, a son, a brother depending on where he is.
3. If different properties and functions of a real world entity is grouped or embedded into a single element, what is it called in OOP language?
a) Inheritance
b) Polymorphism
c) Abstraction
d) Encapsulation
Answer
Answer: d [Reason:] It is Encapsulation, which groups different properties and functions of a real world entity into single element. Abstraction, on other hand, is hiding of functional or exact working of codes and showing only the things which are required by the user.
4. Which of the following is not feature of pure OOP?
a) Classes must be used
b) Inheritance
c) Data may/may not be declared using object
d) Functions Overloading
Answer
Answer: c [Reason:] Data must be declared using objects. Object usage is mandatory because it in turn calls its constructors, which in turn must have a class defined. If object is not used, it is violation of pure OOP concept.
5. Which among the following doesn’t come under OOP concept?
a) Platform independent
b) Data binding
c) Message passing
d) Data hiding
Answer
Answer: a [Reason:] Platform independence is not feature of OOP. C++ supports OOP but it’s not a platform independent language. Platform independence depends on programming language.
6. Which feature of OOP is indicated by the following code?
class student{ int marks; }; class topper:public student{ int age; topper(int age){ this.age=age; } };
a) Inheritance
b) Polymorphism
c) Inheritance and polymorphism
d) Encapsulation and Inheritance
Answer
Answer: d [Reason:] Encapsulation is indicated by use of classes. Inheritance is shown by inheriting the student class into topper class. Polymorphism is not shown here because we have defined the constructor in topper class but that doesn’t mean that default constructor is overloaded.
7. Which feature may be violated if we don’t use classes in a program?
a) Inheritance can’t be implemented
b) Object must be used is violated
c) Encapsulation only is violated
d) Basically all the features of OOP gets violated
Answer
Answer: d [Reason:] All the features are violated because Inheritance and Encapsulation won’t be implemented. Polymorphism and Abstraction is still possible in some cases, but the main features like data binding, object use and etc won’t be used hence use of class is must for OOP concept.
8. How many basic features of OOP are required for a programming language to be purely OOP?
a) 7
b) 6
c) 5
d) 4
Answer
Answer: a [Reason:] There are 7 basic features that define whether a programing language is pure OOP or not. The 4 basic features are inheritance, polymorphism, encapsulation and abstraction. Further, one is, object use is must, secondly, message passing and lastly, Dynamic binding.
9. The feature by which one object can interact with another object is:
a) Data transfer
b) Data Binding
c) Message Passing
d) Message reading
Answer
Answer: c [Reason:] The interaction between two object is called message passing feature. Data transfer is not feature of OOP. Also, message reading is not feature of OOP.
10. _____ underlines the feature of Polymorphism in a class.
a) Nested class
b) Enclosing class
c) Inline function
d) Virtual Function
Answer
Answer: d [Reason:] Virtual Functions can be defined in any class using the keyword virtual. All the classes which inherit the class containing the virtual function, define the virtual function as required. Redefining the function on all the derived classes according to class and use represents polymorphism.
11. Which feature in OOP is used to allocate additional function to a predefined operator in any language?
a) Operator Overloading
b) Function Overloading
c) Operator Overriding
d) Function Overriding
Answer
Answer: a [Reason:] The feature is operator overloading. There is not feature named operator overriding specifically. Function overloading and overriding doesn’t give addition function to any operator.
12. Which among doesn’t illustrates polymorphism?
a) Function overloading
b) Function overriding
c) Operator overloading
d) Virtual function
Answer
Answer: b [Reason:] Function overriding doesn’t illustrate polymorphism because the functions are actually different and theirs scopes are different. Function and operator overloading illustrate proper polymorphism. Virtual functions show polymorphism because all the classes which inherit virtual function, define the same function in different ways.
13. Exception handling is feature of OOP. (True/False)
a) True
b) False
Answer
Answer: a [Reason:] Exception handling is feature of OOP as it includes classes concept in most of the cases. Also it may come handy while using inheritance.
14. Which among the following, for a pure OOP language, is true?
a) The language should follow 3 or more features of OOP
b) The language should follow at least 1 feature of OOP
c) The language must follow only 3 features of OOP
d) The language must follow all the rules of OOP
Answer
Answer: d [Reason:] The language must follow all the rules of OOP to be called a purely OOP language. Even if a single OOP feature is not followed, then it’s known to be a partially OOP language.
15. OOP provides better security than POP:
a) Always true for any programming language
b) May not be true with respect to all programming languages
c) It depends on type of program
d) It’s vice-versa is true
Answer
Answer: a [Reason:] It is always true as we have the facility of private and protected access specifiers. Also, only the public and global data is available globally or else program should have proper permission to access the private data.
Object Oriented MCQ Set 3
1. Which among the following best describes constructor overloading?
a) Defining one constructor in each class of a program
b) Defining more than one constructor in single class
c) Defining more than one constructor in single class with different signature
d) Defining destructor with each constructor
Answer
Answer: c [Reason:] If more than one constructors are defined in a class with same signature, then that results in error. The signatures must be different. So that the constructors can be differentiated.
2. Can constructors be overloaded in derived class?
a) Yes, always
b) Yes, if derived class has no constructor
c) No, programmer can’t do it
d) No, never
Answer
Answer: d [Reason:] The constructor must be having the same name as that of a class. Hence a constructor of one class can’t even be defined in another class. Since the constructors can’t be defined in derived class, it can’t be overloaded too, in derived class.
3. Does constructor overloading include different return types for constructors to be overloaded?
a) Yes, if return types are different, signature becomes different
b) Yes, because return types can differentiate two functions
c) No, return type can’t differentiate two functions
d) No, constructors doesn’t have any return type
Answer
Answer: d [Reason:] The constructors doesn’t have any return type. When we can’t have return type of a constructor, overloading based on the return type is not possible. Hence only parameters can be different.
4. Which among the following is possible way to overload constructor?
a) Define default constructor, 1 parameter constructor and 2 parameter constructor
b) Define default constructor, zero argument constructor and 1 parameter constructor
c) Define default constructor, and 2 other parameterized constructors with same signature
d) Define 2 default constructors
Answer
Answer: a [Reason:] All the constructors defined in a class must have different signature in order to be overloaded. Here one default and other parameterized constructors are used, wherein one is of only one parameter and other accepts two. Hence overloading is possible.
5. Which constructor will be called from the object created in the code below?
class A { int i; A() { i=0; cout<<i; } A(int x=0) { i=x; cout<<I; } }; A obj1;
a) Default constructor
b) Parameterized constructor
c) Compile time error
d) Run time error
Answer
Answer: c [Reason:] When a default constructor is defined and another constructor with 1 default value argument is defined, creating object without parameter will create ambiguity for the compiler. The compiler won’t be able to decide which constructor should be called, hence compiler time error.
6. Which among the following is false for a constructor?
a) Constructors doesn’t have a return value
b) Constructors are always user defined
c) Constructors are overloaded with different signature
d) Constructors may or may not have any arguments being accepted
Answer
Answer: b [Reason:] The constructors are not always user defined. The construct will be provided implicitly from the compiler if the used doesn’t defined any constructor. The implicit constructor makes all the string values null and allocates memory space for each data member.
7. When is the constructor called for an object?
a) As soon as overloading is required
b) As soon as class is derived
c) As soon as class is created
d) As soon as object is created
Answer
Answer: d [Reason:] The constructor is called as soon as the object is created. The overloading comes into picture as to identify which constructor have to be called depending on arguments passed in creation of object.
8. Which among the following function can be used to call default constructor implicitly in java?
a) this()
b) that()
c) super()
d) sub()
Answer
Answer: a [Reason:] The function this() can be used to call the default constructor from inside any other constructor. This helps to further reuse the code and not to write the redundant data in all the constructors.
9. Why do we use constructor overloading?
a) To use different types of constructors
b) Because it’s a feature provided
c) To initialize the object in different ways
d) To differentiate one constructor from another
Answer
Answer: c [Reason:] The constructors are overloaded to initialize the objects of a class in different ways. This allows us to initialize the objet with either default values or used given values. If data members are not initialized then program may give unexpected results.
10. If programmer have defined parameterized constructor only, then ______
a) Default constructor will not be created by the compiler implicitly
b) Default constructor will be created by the compiler implicitly
c) Default constructor will not be created but called at runtime
d) Compiler time error
Answer
Answer: a [Reason:] When the programmer doesn’t specify any default constructor and only defines some parameterized constructor. The compiler doesn’t provide any default constructor implicitly. This is because it is assumed that the programmer will create the objects only with constructors.
11. Which among the following is not valid in java?
a) Constructor overloading
b) Recursive constructor call
c) Default value constructors
d) String argument constructor
Answer
Answer: b [Reason:] Java doesn’t provide the feature to recursively call the constructor. This is to eliminate the out of memory error in some cases that arises unexpectedly. That is an predefined condition for constructors in java.
12. Which constructor will be called from the object obj2 in the following program?
class A { int i; A() { i=0; } A(int x) { i=x+1; } A(int y, int x) { i=x+y; } }; A obj1(10); A obj2(10,20); A obj3;
a) A(int x)
b) A(int y)
c) A(int y, int x)
d) A(int y; int x)
Answer
Answer: c [Reason:] The two argument constructor will be called as we are passing 2 arguments to the object while creation. The arguments will be passed together and hence compiler resolves that two argument constructor have to be called.
13. What is we only create an object but don’t call any constructor for it in java?
a) Implicit constructor will be called
b) Object is initialized to some null values
c) Object is not created
d) Object is created but points to null
Answer
Answer: d [Reason:] The object becomes a reference object which can be initialized will another object. Then this object will indirectly become another name of the object being assigned. If not assigned, it simply points to null address.
14. Which among the following is false?
a) Constructor can’t be overloaded in Kotlin
b) Constructors can’t be called recursively in java
c) Constructors can be overloaded in C++
d) Constructors overloading depends on different signatures
Answer
Answer: a [Reason:] Kotlin language allows constructor overloading. This is a basic feature for the constructors. The constructor overloading allows the object to be initialized according to the user.
15. Which is correct syntax?
a) classname objectname= new() integer;
b) classname objectname= new classname;
c) classname objectname= new classname();
d) classname objectname= new() classname();
Answer
Answer: c [Reason:] The syntax for object creating in java with calling a constructor for is it is as in option c. The syntax must contain the classname followed by the object name. The kwyword new must be used and then the constructor call with or without the parameters as required.
Object Oriented MCQ Set 4
1. Which is the pointer which denotes the object calling the member function?
a) Variable pointer
b) This pointer
c) Null pointer
d) Zero pointer
Answer
Answer: b [Reason:] The pointer which denotes the object calling the member function is known as this pointer. The this pointer is usually used when there are members in the function with same name as those of the class members.
2. Which among the following is true?
a) this pointer is passed implicitly when member functions are called
b) this pointer is passed explicitly when member functions are called
c) this pointer is passed with help of pointer member functions are called
d) this pointer is passed with help of void pointer member functions are called
Answer
Answer: a [Reason:] When an object calls some member function, it implicitly passes itself as an argument. This allows the compiler to know which member should be used for the purposes. This also allows to reduce the ambiguity among the variable and data member names.
3. The this pointer is accessible ______
a) Within all the member functions of the class
b) Only within functions returning void
c) Only within non-static functions
d) Within the member functions with zero arguments
Answer
Answer: c [Reason:] The this pointer is available only within the non-static member functions of a class. If the member function is static, it will be common to all the objects and hence a single object can’t refer to those functions independently.
4. An object’s this pointer _____
a) Isn’t part of class
b) Isn’t part of program
c) Isn’t part of compiler
d) Isn’t part of object itself
Answer
Answer: d [Reason:] The object’s this pointer being called are not part of the object itself. This can be cross verified by checking that it doesn’t take up any space for the data to be stored or pointed.
5. The result of sizeof() function ______
a) Includes space reserved for this pointer
b) Includes space taken up by the address pointer by this pointer
c) Doesn’t include the space taken by this pointer
d) Doesn’t include space for any data member
Answer
Answer: c [Reason:] The space taken by this pointer is not reflected in by the sizeof() operator. This is because object’s this pointer is not part of object itself. This is a cross verification for the concept stating that this pointer doesn’t take any space in the object.
6. Whenever non-static member functions are called ___
a) Address of the object is passed implicitly as an argument
b) Address of the object is passed explicitly as an argument
c) Address is specified globally so that the address is not used again
d) Address is specified as return type of the function
Answer
Answer: a [Reason:] The address is passed implicitly as an argument to the function. This doesn’t have to be passed explicitly. The address is passed, of the object which is calling the non-static member function.
7. Which is the correct interpretation of the member function call from an object, object.function(parameter);
a) object.function(&this, parameter)
b) object(&function,parameter)
c) function(&object,¶meter)
d) function(&object,parameter)
Answer
Answer: d [Reason:] The function name is specified first and then the parameter lists. The parameter list is included with the object name along with & symbol. This denotes that the address of the object is being passed as an argument.
8. The address of the object _____
a) Can’t be accessed from inside the function
b) Can’t be accessed in the program
c) Is available inside the member function using this pointer
d) Can be accessed using the object name inside the member function
Answer
Answer: c [Reason:] The address of the object with respect to which the member functions are being called, are stored in this pointer. This pointer is hence used whenever there are members with same name as those of the variables inside the function.
9. Which among the following is true?
a) This pointer can be used to guard against any kind of reference
b) This pointer can be used to guard against self-reference
c) This pointer can be used to guard from other pointers
d) This pointer can be used to guard from parameter referencing
Answer
Answer: b [Reason:] The this pointer can be used to guard itself whenever self-reference is used. This allows accidental address access. And accidental modification of data.
10. Which syntax doesn’t execute/is false when executed?
a) if(&object != this)
b) if(&function !=object)
c) this.if(!this)
d) this.function(!this)
Answer
Answer: a [Reason:] The condition becomes false when executed and hence doesn’t executes. This is the case where this pointer can guard itself from the self-reference. Here if the address of the object doesn’t match with this pointer that means the object doesn’t refer itself.
11. The this pointers _____
a) Are modifiable
b) Can be assigned any value
c) Are made variables
d) Are non-modifiable
Answer
Answer: d [Reason:] The this pointer is non modifiable. This is because the address of any object remains constant throughout its life time. Hence the address must not be changed otherwise wrong members of invalid addresses might get accessed.
12. Earlier implementations of C++ ___
a) Never allowed assignment to this pointer
b) Allowed no assignment to this pointer
c) Allowed assignments to this pointer
d) Never allowed assignment to any pointer
Answer
Answer: c [Reason:] The earlier, most initial versions of C++ used to allow assignments to this pointers. That used to allow modifications of this pointer. Later that feature got disabled.
13. This pointer can be used directly to _____
a) To manipulate self-referential data structures
b) To manipulate any reference to pointers to member functions
c) To manipulate class references
d) To manipulate and disable any use of pointers
Answer
Answer: a [Reason:] This is a feature provided, that can be used directly. The manipulation of self-referential data structures is just an application of this feature. Other conditions fails as this pointer doesn’t deal with those things.
14. Which among the following is/are type(s) of this pointer?
a) const
b) volatile
c) const or volatile
d) int
Answer
Answer: c [Reason:] The this pointer can be declared const or volatile. This depends on need of program and type of code. This is just an additional feature.
15. Which is the correct syntax for declaring type of this in a member function?
a) classType [cv-qualifier-list] *const this;
b) classType const[cv-qualifier-list] *this;
c) [cv-qualifier-list]*const classType this;
d) [cv-qualifier-list] classType *const this;
Answer
Answer: d [Reason:] The syntax contains the cv-qualifier-list that can be determined from the member function declaratory that can be either const or volatile or can be made both. Hence we write it as list. classType denotes the name of class to mention to which class does the object belong to. And *const this denotes that the this pointer is having a constant value.
Object Oriented MCQ Set 5
1. Which among the following best describes polymorphism?
a) It is the ability for a message/data to be processed in more than one form
b) It is the ability for a message/data to be processed in only 1 form
c) It is the ability for many messages/data to be processed in one way
d) It is the ability for undefined message/data to be processed in at least one way
Answer
Answer: a [Reason:] It is actually the ability for a message / data to be processed in more than one form. The word polymorphism indicates many-forms. So if a single entity takes more than one form, it is known as polymorphism.
2. What do you call the languages that support classes but not polymorphism?
a) Class based language
b) Procedure Oriented language
c) Object-based language
d) If classes are supported, polymorphism will always be supported
Answer
Answer: c [Reason:] The languages which support classes but doesn’t support polymorphism, are known as object-based languages. Polymorphism is such an important feature, that is a language doesn’t support this feature, it can’t be called as a OOP language.
3. Which among the following is the language which supports classes but not polymorphism?
a) SmallTalk
b) Java
c) C++
d) Ada
Answer
Answer: d [Reason:] Ada is the language which supports the concept of classes but doesn’t support the polymorphism feature. It is an object-based programming language. Note that it’s not an OOP language.
4. If same message is passed to objects of several different classes and all of those can respond in a different way, what is this feature called?
a) Inheritance
b) Overloading
c) Polymorphism
d) Overriding
Answer
Answer: c [Reason:] The feature defined in question defines polymorphism feature. Here the different objects are capable of responding to the same message in different ways, hence polymorphism.
5. Which class/set of classes can illustrate polymorphism in the following code:
abstract class student { public : int marks; calc_grade(); } class topper:public student { public : calc_grade() { return 10; } }; class average:public student { public : calc_grade() { return 20; } }; class failed{ int marks; };
a) Only class student can show polymorphism
b) Only class student and topper together can show polymorphism
c) All class student, topper and average together can show polymorphism
d) Class failed should also inherit class student for this code to work for polymorphism
Answer
Answer: c [Reason:] Since Student class is abstract class and class topper and average are inheriting student, class topper and average must define the function named calc_grade(); in abstract class. Since both the definition are different in those classes, calc_grade() will work in different way for same input from different objects. Hence it shows polymorphism.
6. Which type of function among the following shows polymorphism?
a) Inline function
b) Virtual function
c) Undefined functions
d) Class member functions
Answer
Answer: b [Reason:] Only virtual functions among these can show polymorphism. Class member functions can show polymorphism too but we should be sure that the same function is being overloaded or is a function of abstract class or something like this, since we are not sure about all these, we can’t say whether it can show polymorphism or not.
7. In case of using abstract class or function overloading, which function is supposed to be called first?
A) Local function
B) Function with highest priority in compiler
C) Global function
D) Function with lowest priority because it might have been halted since long time, because of low priority
Answer
Answer: b [Reason:] Function with highest priority is called. Here, it’s not about the thread scheduling in CPU, but it focuses on whether the function in local scope is present or not, or if scope resolution is used in some way, or if the function matches the argument signature. So all these things define which function has the highest priority to be called in runtime. Local function could be one of the answer but we can’t say if someone have used pointer to another function or same function name.
8. Which among the following can’t be used for polymorphism?
a) Static member functions
b) Member functions overloading
c) Predefined operator overloading
d) Constructor overloading
Answer
Answer: a [Reason:] Static member functions are not property of any object. Hence it can’t be considered for overloading/overriding. For polymorphism, function must be property of object, not only of class.
9. What is output of the following program?
class student { public : int marks; void disp() { cout<<”its base class” }; class topper:public student { public : void disp() { cout<<”Its derived class”; } } void main() { student s; topper t; s.disp(); t.disp(); }
a) Its base classIts derived class
b) Its base class Its derived class
c) Its derived classIts base class
d) Its derived class Its base class
Answer
Answer: a [Reason:] You need to focus on how the output is going to be shown, no space will be given after first message from base class. And then the message from derived class will be printed. Function disp() in base class overrides the function of base class being derived.
10. Which among the following can show polymorphism?
a) Overloading ||
b) Overloading +=
c) Overloading <<
d) Overloading &&
Answer
Answer: c [Reason:] Only insertion operator can be overloaded among all the given options. And the polymorphism can be illustrated here only if any of these is applicable of being overloaded. Overloading is type of polymorphism.
11. Find the output of the program:
class education { char name[10]; public : disp() { cout<<”Its education system”; } class school:public education { public: void dsip() { cout<<”Its school education system”; } }; void main() { school s; s.disp(); } }
a) Its school education system
b) Its education system
c) Its school education systemIts education system
d) Its education systemIts school education system
Answer
Answer: a [Reason:] Notice that the function name in derived class is different from the function name in base class. Hence when we call the disp() function, base class function is executed. No polymorphism is used here.
12. Polymorphism is possible in C language.
a) True
b) False
Answer
Answer: a [Reason:] It is possible to implement polymorphism in C language, even though it doesn’t support class. We can use structures and then declare pointers which in turn points to some function. In this way we simulate the functions like member functions but not exactly member function. Now we can overload these functions, hence implementing polymorphism in C language.
13. Which problem may arise if we use abstract class functions for polymorphism?
a) All classes are converted as abstract class
b) Derived class must be of abstract type
c) All the derived classes must implement the undefined functions
d) Derived classes can’t redefine the function
Answer
Answer: c [Reason:] The undefined functions must be defined is a problem, because one may need to implement few undefined functions from abstract class, but he will have to define each of the functions declared in abstract class. Being useless task, it is a problem sometimes.
14. Which among the following is not true for polymorphism?
a) It is feature of OOP
b) Ease in readability of program
c) Helps in redefining the same functionality
d) Increases overhead of function definition always
Answer
Answer: d [Reason:] It never increases function definition overhead, one way or other if you don’t use polymorphism, you will use the definition in some other way, so it actually helps to write efficient codes.
15. If 2 classes derive one base class and redefine a function of base class, also overload some operators inside class body. Among these two things of function and operator overloading, where is polymorphism used?
a) Function overloading only
b) Operator overloading only
c) Both of these are using polymorphism
d) Either function over loading or operator overloading because polymorphism can be applied only once in a program
Answer
Answer: d [Reason:] Both of them are using polymorphism. It is not a necessary that polymorphism can be used only once in a program, it can be used anywhere, any number of times in a single program.
