Explore topic-wise InterviewSolutions in .

Correct choice is (B) Constructor

The best explanation: Constructors are the MEMBER functions which are called automatically WHENEVER an object is created. It is a mandatory functions to be called for an object to be created as this helps in initializing the object to a LEGAL initial value for the class.

Right option is (d) class STUDENT{ public: student(){} };

Explanation: The constructors must not have any RETURN type. Also, the body may or may not contain any body. Defining DEFAULT constructor is optional, if you are not USING any other constructor.

Correct answer is (a) 2

To explain: TWO types of CONSTRUCTORS are defined GENERALLY, namely, default constructor and parameterized constructor. Default constructor is not NECESSARY to be defined always.

The correct answer is (d) CONSTRUCTOR of A then B, finally C

The explanation is: While creating the OBJECT of CLASS C, its constructor would be CALLED by DEFAULT. But, if the class is inheriting some other class, firstly the parent class constructor will be called so that all the data is initialized that is being inherited.

Right ANSWER is (B) It can be defined with zero arguments

Easiest explanation - It can’t be defined with zero number of arguments. This is because to copy ONE OBJECT to another, the object must be mentioned so that COMPILER can take values from that object.

The CORRECT choice is (c) Compiler will give out of memory error

The explanation is: Compiler runs out of memory. This is because while PASSING the argument by VALUE, a constructor of the OBJECT will be called. That in turn called another object constructor for values, and this GOES on. This is like a constructor call to itself, and this goes on infinite times, hence it must be passed by reference, so that the constructor is not called.

Right option is (a) Number of arguments and type of arguments

For EXPLANATION: Each CONSTRUCTOR must DIFFER in the number of arguments it accepts and the type of arguments. This actually defines the constructor signature. This helps to remove the AMBIGUITY and define a unique constructor as REQUIRED.

Correct option is (b) 3

Explanation: There are 3 types of CONSTRUCTORS in general, namely, default constructors, PARAMETERIZED constructors and copy constructors. Default ONE is called whenever an object is CREATED without arguments.

Right CHOICE is (C) Copy

Easiest EXPLANATION - Copy constructor is used while an object is assigned with ANOTHER. This is mandatory since we can’t decide which member should be assigned to which member value. By using copy constructor, we can assign the values in REQUIRED form.

The correct option is (a) CONSTRUCTOR is not called in pass by reference

For explanation: Object must be passed by reference to copy constructor because constructor is not called in pass by reference. Otherwise, in pass by VALUE, a temporary object will be created which in turn will try to call its constructor that is ALREADY being used. This results in CREATING infinite NUMBER of objects and hence memory shortage error will be shown.

The correct choice is (d) Explicit

The best I can explain: The KEYWORD explicit can be USED while DEFINING the constructor only. This is used to SUPPRESS the implicit call to the constructor. It ensures that the CONSTRUCTORS are being called with the default syntax only (i.e. only by using object and constructor name).

Right answer is (c) Default constructor can be CALLED explicitly

Easiest explanation - Default constructors can be called explicitly ANYTIME. They are specifically used to ALLOCATE memory space for the object in memory, in general. It is not necessary that these should ALWAYS be called implicitly.

Correct option is (d) Constructors don’t have a return TYPE

Explanation: Constructors don’t return any value. Those are special functions, WHOSE return type is not defined, not even void. This is so because the constructors are meant to initialize the members of CLASS and not to perform some task which can return some value to NEWLY CREATED object.

The correct CHOICE is (c) STATIC constructors can’t be parameterized constructors

The BEST I can explain: Static constructors can’t be parameterized constructors. Those are used to INITIALIZE the value of static members only. And that must be a definite value. Accepting arguments may MAKE it possible that static members loses their value with every new object being created.

The correct option is (a) True

Explanation: Since the STATIC constructors are can’t be parameterized, they can’t be OVERLOADED. Having this CASE, only one constructor will be possible to be created in a local scope, because the signature will always be same and hence it will not be possible to overload static constructor.

Right choice is (d) All NUMERIC member with zero and strings to null

To EXPLAIN: Default constructor, which even the programmer doesn’t define, always initialize the values as zero if numeric and null if string. This is DONE so as to avoid the ACCIDENTAL values to change the conditional statements being used and similar conditions.

Right choice is (a) The CLASS can’t be inherited

The best I can explain: If the CONSTRUCTORS are defined in private access, then the class can’t be inherited by other classes. This is useful when the class contains static members only. The INSTANCES can NEVER be CREATED.

Correct option is (d) Creates an OBJECT by initializing it with ANOTHER PREVIOUSLY created object of same class

Easy 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.

Right CHOICE is (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.

The correct answer is (c) No, not possible

Easiest 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 correct option is (B) Copy an OBJECT so that it can be passed to a function

The explanation is: 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.

The CORRECT choice is (a) Compiler provides an implicit copy CONSTRUCTOR

To explain I would SAY: The compiler provides an implicit copy constructor. It is not mandatory to always create an explicit copy constructor. The values are copied USING implicit constructor only.

Correct CHOICE is (a) Copy constructor must be defined

The best explanation: In the case where DYNAMIC memory allocation is used, the copy constructor definition must be given. The IMPLICIT copy constructor is not capable of manipulating the dynamic memory and pointers. Explicit definition allows to manipulate the DATA as REQUIRED.

The correct choice is (c) CLASSNAME (cont classname &obj){ /*constructor definition*/ }

To explain: The syntax must contain the class name first, followed by the classname as type and &object within PARENTHESIS. Then comes the constructor BODY. The definition can be given as PER requirements.

Right answer is (a) Must be passed by REFERENCE

Explanation: This is mandatory to pass the OBJECT by reference. Otherwise, the object will TRY to create another object to copy its values, in turn a constructor will be called, and this will keep on calling itself. This will cause the compiler to give out of memory ERROR.

Right answer is (d) Is not passed by reference

Easiest explanation - All the OPTIONS given, directly or INDIRECTLY indicate that the object is being passed by reference. And if object is not passed by reference then the out of memory ERROR is produced. DUE to infinite CONSTRUCTOR call of itself.

Correct option is (c) GENERATES TEMPORARY object

To EXPLAIN: Whenever the compiler creates a temporary object, COPY constructor is used to copy the VALUES from existing object to the temporary object.

Correct choice is (B) USER defined copy constructor

The best explanation: While using explicit copy constructor, the pointers of COPIED object POINT to the intended memory location. This is assured since the PROGRAMMERS themselves manipulate the addresses.

The correct choice is (a) Yes, always

Easy explanation - The copy CONSTRUCTOR can be defined as private. If we make it private then the OBJECTS of the class can’t be copied. It can be used when a class used DYNAMIC memory allocation.

The CORRECT ANSWER is (a) Must be const

To explain I would say: The object should not be modified in the copy CONSTRUCTOR. Because the object itself is being copied. When the object is RETURNED from a function, the object must be a CONSTANT otherwise the compiler creates a temporary object which can die anytime.

The CORRECT option is (a) True

The best EXPLANATION: The COPY constructors are always overloaded constructors. They have to be. All the classes have a default constructor and other constructors are BASICALLY overloaded constructors.

Right answer is (c) DEFINING more than one constructor in single CLASS with different signature

For explanation: 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.

The correct OPTION is (d) No, never

Easy explanation - 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.

Right answer is (B) Constructors are always USER defined

For explanation: 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.

The CORRECT option is (d) As SOON as OBJECT is created

Explanation: 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 the creation of object.

Right choice is (c) To INITIALIZE the object in DIFFERENT ways

Explanation: The constructors are overloaded to initialize the objects of a class in different ways. This allows us to initialize the object with either default values or used given values. If data members are not initialized then program may give UNEXPECTED RESULTS.

Right choice is (a) Default CONSTRUCTOR will not be CREATED by the compiler implicitly

To explain I would SAY: 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.

Correct choice is (d) Object is created but POINTS to null

The best explanation: 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.