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C++ programming language part: 50 Constructor

November 11, 2017 bappi ashraf

Constructor

Every object created would have a copy of member data. The above program, the object K of thwe class nova had to call a member function called data_in() , there is no possibility of member data getting initialize automatically. This automac initialization is performed through the use of constructor functions. So a constructor function is a special function that is a member of the class and has the same name as that of the class.

Program 40-1

//class & object.demo

#include

class nova //class defined

{ private:

int age; // we can't type age=30,name[10]=bappi

char name[10]; // so we need a 'constructor'

public:

nova(); //default constructor

nova(int a, char* b); // defined constructor

void data_in(); // member function

void data_out();

};

nova::nova()

{ cout<<" Look! It's invocked "<

nova::nova(int a, char* b) // constructor & class would be the same name

{ a=age;

b=name; }

void nova::data_in() //member function

{ cout<<" Type your age "<

cin>>age;

cout<<"Type your name "<

cin>>name; }

void nova::data_out() //scope resolution operator

{ cout<<" The age is "<

cout<<" The name is "<

void main()

{

nova k; // k is called object

k.data_in(); //would be k->data_in() if pointer

k.data_out();

getch();

}

Program 40_2

//class & object.demo

#include

class nova //class defined

{

private:

int p1,p2,p3; // we can't type p1=5 likk, need a 'constructor'

public:

nova(); //default constructor

nova(int,int); // defined constructor

void data_in(int,int); // member function

void sum();

void data_out();

};

nova::nova()

{ cout<<" Look! It's invocked "<

p1=p2=p3=0; }

nova::nova(int x,int y) // constructor & class would be the same name

{ cout<<" two constructor are called "<

p1=x;

p2=y; }

void nova::data_in(int a,int b) //member function

{

p1=a;

p2=b;

}

void nova::sum()

{

p3=p1+p2;

}

void nova::data_out() //scope resolution operator

{

cout<<" The sum is= "<

}

void main()

{

nova k1,k2(4,3),*k3; // k is called object

k3=new nova(5,10); // new value are assign

k2.sum(); //this is from initialize member data

k3->sum();

k3->data_out();

k2.data_out();

}

part: 01 Programming Language

part: 02 Compiler

part: 03 Programming Logic

part: 04 Data Type

part: 05 Programming in C++

part: 06 Data Type

part: 07 Get Input from keyboard

part: 08 Operators

part: 09 Arithmetic AssignmentOperators

part: 10 Identifies of Characters

part: 11 do.. while loop

part: 12 unary operators( Incrementand decrement)

part: 13 Decrement

part: 14 for loop

part: 16 Conditional/ternary Operator

part: 17 Break

part: 18 The continue statementforces the next iteration of the loop to take place.

part: 19 Arrays

part: 20 Array Address

part: 21 Arrays and Pointer

part: 22 Two dimensional array

part: 23 Function

part: 24 Function Argument

part: 25 Calling Function

part: 26 Return Values

part: 27 Over Loading Function

part: 29 More about function andothers

part: 30 Passing arrays to function

part: 31 Dynamic memory allocation

part: 32 Library function

part: 33 User define mathematicalfunction (square)

part: 34 I/O Function

part: 35 Boolean Functions

part: 36 Look here's two differentuser define Boolean Functions

part: 37 Function Scope

part: 38 String

part: 39 String I/O

part: 40 Some dafault member function

part: 41 Standard String-Handlingfunction

part: 42 String Array

part: 43 User defined data type

part: 45 Data Storage Type

part: 46 Sratic storage type

part: 47 Extern storage type

part: 48 Classes and Objects

part: 49 Scope Resolution Operator

part: 50 Constructor

part: 51 Destructor

part: 52 Inheritance

part: 53 Overriding Base ClassMembers

part: 54 Scope Resolution with OverriddenMembers

part: 55 Base Class Initialization

part: 56 Multiple Inheritance

part: 57 Protected base ClassInheritance

part- 58 Ambiguity of MultipleClasses

part- 59 Virtual Base Class

part- 60 More about Constructor andDestructor

part- 61 Virtual Function andpolymorphism

part- 62 Virtual function withdynamic polymorphism

part- 63 Streams

part- 64 File Input and Output withabstract data types

part- 65 Writing and Readingcharacter using binary functions

part- 66 The get() function

part- 67 String Input

part- 68 Integer Input and Output

part- 69 File Pointers

part- 70 More abuot Integer Input and Output

part- 71 Exercise:

part- 72 Operator overloading

part- 73 Look here is a program witha class and overload the ==,>,< and += operators

part- 74 Linked List

part- 75 Representing a Node

part- 76 Inserting and Traversing a Node

part- 77 Deleting a Node

part- 78 More about Linked List

part- 79 Programming Logic andTechnique

part- 81 Programming Logic and Technique:

part- 82 Programming Logic andTechnique:

part- 83 Programming Logic andTechnique:

part- 84 Programming Logic andTechnique:

part- 85 Programming Logic and Technique:

Part- 86 assign the content of twostring