vinodsrivastava.com Constructor and Destructor

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1 vinodsrivastava.com Constructor and Destructor Constructor : it is a special member function of class with the following unique features 1. It has the same name as the name of the class they belongs to 2. it has no return type 3. it is defined in public visibility mode 4. it is automatically called at the time of object creation/declaration 5. Constructor function can be overloaded Default constructor: is a constructor without any parameter. It is the constructor added by the compiler when there are no constructor functions defined / declared in a class. class Employee char name[20]; double salary; Employee() strcpy(name, ""); salary=0.0; void inputdata() gets(name); cin>>salary; cout<<name<<","<<salary<<endl; ; Parameterised constructor: is a constructor with parameter and it is always defined by a programmer student(char na[], double ma) strcpy(name, na); marks=ma;

2 void inputdata() gets(name); cout<<name<<","<<marks<<endl; ; Constructor with default parameter: is a parameterised constructor with constant values assigned to the formal parameters of the constructor function. student(char n[]="", double m=0) strcpy(name, n); marks=m; void input() gets(name); cout<<name<<","<<marks<<endl; ; Copy constructor: is a constructor function in which an object of the same class is passed by reference to the constructor function and it is used to duplicate an object when the object is getting created. A copy constructor is added by the compiler when there is no copy constructor defined in the class. student(student& s) strcpy(name, s.name); marks=s.marks; void input() gets(name); cout<<name<<","<<marks<<endl; ; C++ VKS-Learning Hub Page 2

3 Constructor Overloading: A class having more than one constructor functions, that is, objects can be created in more than one ways. student(char n[]="", double m=0) strcpy(name, n); marks=m; student(student& s) strcpy(name, s.name); marks=s.marks; void input() gets(name); cout<<name<<","<<marks<<endl; ; Destructor is a special public member function of a class that destroys an object, when an object goes out of scope. Destructor functions have the following unique characteristics: Destructor function name begin with ~ (tilde character) and followed by class name A destructor function is defined / declared only in the public area of a class A destructor function does not have any return value, not even void A class can have only one destructor Difference between constructor and destructor: Constructor Destructor Constructor name is class name Destructor name is ~ followed by class name A constructor creates an object A destructor deletes an object from memory A class can have many constructors A class can have only one destructor A constructor is invoked to create an object Destructor is invoked automatically Inheritance, Constructor and Destructor: Constructor and destructor functions are never inherited. But constructor and destructor play a very important role in creating object and deleting object, that is, base class constructor will create base class object (resources will be allocated for base class members) and derived class constructor will create derived class objects (resources will be allocated for derived class members). In case of multi-level inheritance, the constructors will be executed in the order of inheritance. While in case of multiple inheritance, the constructors will be executed in the order in which they appear in the declaration of the derived class. Order of execution of destructor will be the reverse order of execution of constructor. C++ VKS-Learning Hub Page 3

4 CBSE 2013 a) Write any two similarities between Constructor and Destructor. Write the function headers for constructor and destructor of a class Flight. b) Answer the questions (i) and (ii) after going through the following class: class Race int CarNo, Track; Race(); // Function 1 Race(int CN); // Function 2 Race(Race &R); // Function 3 void Register(); // Function 4 void Drive(); // Function 5 ; void main() Race R; : (i) Out of the following, which of the option is correct for calling Function 2? Option 1-Race T(30); Option 2-Race U(R); (ii) Name the feature of Object Oriented Programming, which is illustrated by Function 1, Function 2 and Function 3 Combined together CBSE 2012 a) What is the difference between the members in private visibility mode and the members in public visibility mode inside a class? Also, give a suitable C++ code to illustrate both. b) Answer the questions (i) and (ii) after going through the following class: class Tour int LocationCode; char Location[20]; float Charges; Tour() // Function 1 LocationCode=1; strcpy(location, PURI ); Charges=1200; void TourPlan(float C) // Function 2 cout<<locationcode<< : <<Location<< : <<Charges<<endl; Charges += 100; Tour(int LC, char L[], float C) // Function 3 LocationCode=LC; strcpy(location, L); Charges=C; ~Tour() // Function 4 cout<< Tour Plan Cancelled <<endl; ; (i) (ii) In Object Oriented Programming, what are Function 1 and Function 3 combined together referred as? In Object Oriented Programming, which concept is illustrated by Function 4? When is this function called/invoked? C++ VKS-Learning Hub Page 4

5 CBSE 2011 a) Differentiate between members, which are presented within the private visibility mode with those which are present within the public visibility mode? b) Write the output of the following C++ code. Also, write the name of features of Object Oriented Programming used in the following program jointly illustrated by the functions [I] to [IV] #include<iostream.h> void Print() // Function [I] for(int K=1; K<=60; K++) cout<< - ; void Print(int N) // Function [II] for(int K=1; K<=N; K++) cout<< * ; void Print(int A, int B) // Function [III] for(int K=1; K<=B; K++) cout<<a*k; void Print(char T, int N) // Function [IV] for(int K=1; K<=N; K++) cout<<t; void main() int U=9, V=4, W=3; char ; Print(C,V); Print(U,W); CBSE 2010 Marks : 2 1) Answer the questions (i) and (ii) after going through the following class: class TEST int RegNo, Max, Min, Score; TEST () // Function 1 RegNo=101; Max=100; Min=40; Score=75; TEST (int Pregno, int Pscore) // Function 2 Regno = Pregno; Max=100; Min=40; Score=Pscore; ~TEST () // Function 3 cout<< TEST Over <<endl; void Display () // Function 4 cout<<regno<< : <<Max<< : <<Min<<endl; cout<< [Score] <<Score<<endl; ; (i) As per Object Oriented Programming, which concept is illustrated by Function 1 and Function 2 together? (ii) What is Function 3 specifically referred as? When do you think, Function 3 will be invoked/called? C++ VKS-Learning Hub Page 5

6 CBSE 2009 Marks : 4 (a) What is copy constructor? Give an example in C++ to illustrate copy constructor. (b) Answer the questions (i) and (ii) after going through the following class: class WORK int WorkId; char WorkType; ~WORK () // Function 1 cout<< UN-Allocated <<endl; void Status () // Function 2 cout<<workid<< : <<WorkType<<endl; WORK () // Function 3 WorkId = 10; WorkType = T ; WORK ( WORK &W) // Function 4 WorkId = W.WorkId + 12; WorkType = W.WorkType + 1; ; (i) Which member function out of Function 1, Function 2, Function 3 and Function 4 shown in the above definition of class WORK is called automatically, when the scope of an object gets over? IS it known as Constructor OR Destructor OR Overloaded Function OR Copy Constructor? (ii) WORK W; // Statement 1 WORK Y(W); // Statement 2 Which member function out of Function 1, Function 2, Function 3 and Function 4 shown in the above definition of class WORK is called an execution of statement written as statement 2?What is this function specifically known as Destructor OR Copy Constructor OR Default Constructor? CBSE 2008 Marks : 2 3) Answer the question (i) and (ii) after going through visibility modes in context of Object Oriented Programming using a suitable example illustrating each. #include<iostream.h> #include<string.h> class Bazar char Type[20], Product[20]; int Qty; float Price; Bazar () // Function 1 strcpy(type, Electronic ); strcpy(product, Calculator ); Qty = 10; Price = 225; void Disp () // Function 2 cout<<type<< - <<Product<< : <<Price<<endl; ; void main () Bazar B; // Statement 1 B.Disp(); // Statement 2 (i) Will Statement 1 initialize all the data members for object B with the values given in the Function 1? (Yes OR No). Justify your answer suggesting the correction(s) to be made in the above code. (ii) What shall be the possible output when the program gets executed? (Assuming, if required the suggested correction (s) are made in the program) C++ VKS-Learning Hub Page 6

7 CBSE 2007 Marks : 4 4) (a) Differentiate between a constructor and destructor function? (b) Answer the questions (i) and (ii) after going through the following class: class Maths char Chapter[20]; int Marks; Maths () // Function 1 strcpy( Chapter, Geometry ); Marks = 10; cout<< Chapter initialized" ~Maths () // Function 2 cout<< Chapter Over ; ; (i) Name the specific features of class shown by Member function 1 and Member Function 2 in the above example. (ii) How would Member Function 1 and Member Function 2 get executed? CBSE 2006 Marks : 4 5) (a) What is default constructor? How does it differ from destructor? (b) Answer the questions (i) and (ii) after going through the following class: class Interview int month; Interview (int y) // Constructor 1 month = y; Interview (Interview & t); // Constructor 2 ; (i) Create an object, such that it invokes Constructor 1 Write the complete definition for Constructor 2. C++ VKS-Learning Hub Page 7

HOLIDAYS HOMEWORK CLASS : XII. Subject : Computer Science

HOLIDAYS HOMEWORK CLASS : XII. Subject : Computer Science HOLIDAYS HOMEWORK 2017-18 CLASS : XII Subject : Computer Science Note : Attempt the following questions in a separate register and make yourself prepared to conquer the world. Chapter- 1 : C++ Revision