classes c++

CS103-Computer Programming

Object Oriented Programming (OOP)

Objectives:

Classes

Defining Classes and Member Functions

Member Function Definition

The Dot Operator And The Scope Resolution Operator

A Class is a Full-Fledged Type

Public & Private Members

Classes Implementation

Classes Constructors & Destructors

Default Constructor

Parameterized Constructor

Overloaded Constructor

Constructor with Default Parameters

Copy Constructor

Arrays of Class Objects & Constructors

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Classes

CS103-Computer Programming By: Mr. Najeeb -Ur-Rehman


Getting Started

Classes A class is basically a structure with member functions as well as member data. Classes are central to the

programming methodology known as object-oriented programming.

Defining Classes and Member Functions

A class is a type that is similar to a structure type, but a class type normally has member functions as

well as member variables

Member Function Definition

A member function is defined similar to any other function except that the class name and the scope

resolution operator, ::, are given in the function heading.

Syntax

Note that the member variable (month and day) are not preceded by and object name and do not when

they occur in member function definition.

In the function definition for a member function, you can use the names of all members of the class

(both the data members and the function members) without using the dot operator.

The Dot Operator and the Scope Resolution Operator

Both the dot operator and the scope resolution operator used with member names to specify of what

thing they are member.

A Class is a Full-Fledged Type

A class is a type just like int and double. You can have variables of a class type, you can have parameter

of class type, a function can return a value of a class type, and more generally, you can use a class type

like any other type.

Public & Private Members

There is not universal agreement about whether the public members should be listed first or the private

members should be listed first. The majority seem to prefer listing the public members first. This allows

for easy viewing of the portions programmers using the class actually get to use. You can make your own

decision on what you wish to place first, but the examples in the book will go along with the majority

and list the public members first, before the private members.

In one sense, C++ seems to favor private member first. If the first group of members has neither the

public: nor the private: specifier, then members of that group will automatically be private. You will see

this default behavior use in code and should Familiar with it. However, we will not use it in this book.

Classes Implementation A class is a combination of data and functions joined together to form an object type. The object type

defines the operations that are necessary to manipulate the object. By creating a class, we can take

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advantage of data hiding, which is very important in programming. Data hiding is physically located data

in the class (inside the class object type) that is hidden from the "outside", which is everything in the

program not defined in the class type. The data can only be accessed or changed by functions that are

apart of the class. These member functions that provide access to the hidden data are called accessor

methods. The declaration of a class is similar to that of a structure, except that usually there will be

member functions along with data members. There will also be some type of syntax for distinguishing

members that are available for public use and ones that will be kept private.

The best way to learn classes is by studying a simple class object type. The following is a very simple

class object type:

class myClass { private : int data1; public : void setData( int d ) { data1 = d; } void displayData( ) { cout

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#include

#include

#include

using namespace std;

const int MAXNAMELEN = 51;

const int MAXSCHOOLLEN = 101;

class Student

{ // ********* Private data member **************

private:

char school[MAXSCHOOLLEN];

char name[MAXNAMELEN];

int id;

int rank;

double cumulativeGpa;

public:

void setSchool(char inSchool[]); // accessor methods

void setName(char inName[]);

void setId(int inId);

void setRank(int inRank);

void setGpa(double inGpa);

void displayData();

};

int main( )

{

Student stu1;

char stuName[MAXNAMELEN], schName[MAXSCHOOLLEN];

int idNum, rank;

double gpa;

cout rank;

cout > gpa;

stu1.setName(stuName);

stu1.setSchool(schName);

stu1.setId(idNum);

stu1.setRank(rank);

stu1.setGpa(gpa);

stu1.displayData();

cout

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return EXIT_SUCCESS;

}

void Student :: setSchool(char inSchool[])

{

strncpy(school, inSchool, MAXSCHOOLLEN);

}

void Student :: setName(char inName[])

{

strncpy(name, inName, MAXNAMELEN);

}

void Student :: setId(int inId)

{

id = inId;

}

void Student :: setRank(int inRank)

{

rank = inRank;

}

void Student :: setGpa(double inGpa)

{

cumulativeGpa = inGpa;

}

void Student :: displayData()

{

cout

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*/

// a Complete example by declaring, using structs as well as data members.

#include

#include


class CDAccountV1

{

double balance;

double interestRate;

int term;

};

void main()

{ CDAccountV1 a,b;

a.balance=500.0;

a.interestRate=0.10;

a.term=1;

cout

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void setroomID(int);

void setnumberOfChairs(int);

void setboardType(char);

void setmultimedia(string);

void setremarks(string);

int getroomID();

int getnumberOfChairs();

char getboardType();

string getmultimedia();

string getremarks();

void display();

};

void main ()

{

ClassRoom CR0;

CR0.display();

system("PAUSE");

}

//--------------------------------------Constructors

ClassRoom::ClassRoom()

{

this->roomID=0;

this->numberOfChairs=0;

this->boardType='M';

this->multimedia="New";

this->remarks="Default Constructor";

}

//--------------------------------------Getter Functions

int ClassRoom::getroomID()

{

return this->roomID;

}

int ClassRoom::getnumberOfChairs()

{

return this->numberOfChairs;

}

char ClassRoom::getboardType()

{

return (this->boardType);

}

string ClassRoom::getmultimedia()

{

return this->multimedia;

}

string ClassRoom::getremarks()

{

return this->remarks;

}

//------------------------------------Printing Functions

void ClassRoom::display()

{

cout

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cout

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this->setmultimedia(mul); //this->multimedia=str;

this->setremarks(remks+"\nConstructor with All(5)Parameters

(ID,NOC,BoardType,Multimedia,Remarks)");

}

//---------------------------------------Setter Functions

void ClassRoom::setroomID(int id)

{

this->roomID=id;

}

void ClassRoom::setnumberOfChairs(int NOC)

{

this->numberOfChairs=NOC;

}

void ClassRoom::setboardType(char c)

{

this->boardType=c;

}

void ClassRoom::setmultimedia(string str)

{

this->multimedia=str;

}

void ClassRoom::setremarks(string str)

{

this->remarks=str;

}



{


}


{


}


{


}


{


}


{


}



{

cout

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/*

Room ID : 11

N.O. Chairs : 25

Board Type : M

Multimedia : Repairing..

Remarks :

Remarks added from Main

Constructor with All(5)Parameters (ID,NOC,BoardType,Multimedia,Remarks)

----------------------------------

Press any key to continue . . .

*/

Overloaded Constructor

Given example demonstrates the concept of overloaded constructor.

class ClassRoom {

private:

// Other class data members as in above example

public:

ClassRoom();

ClassRoom(int id);

ClassRoom(int id,int NOC);

ClassRoom(int id,int NOC,char c);

ClassRoom(int id,int NOC,char,string mul);

ClassRoom(int id,int NOC,char,string mul, string rmks);

};

void main ()

{

ClassRoom CR0,CR1(1),CR2(2,30),CR3(3,35,'M'),

CR4(4,40,'M',"Repairing.."),CR5(5,40,'M',"Repairing..","Remarks

added from Main");

CR0.display();

CR1.display();

CR2.display();

CR3.display();

CR4.display();

CR5.display();

system("PAUSE");

}

//--------------------------------------Constructors

ClassRoom::ClassRoom()

{

this->roomID=0;

this->numberOfChairs=0;

this->boardType='M';

this->multimedia="New";

this->remarks="Default Constructor";

}

ClassRoom::ClassRoom(int id)

{

this->roomID=id;

this->setnumberOfChairs(0);

this->setboardType('M');

this->setmultimedia("New");

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this->remarks="Constructor with 1-Parameter (ID) ";

}

ClassRoom::ClassRoom(int id,int NOC)

{

this->roomID=id;


this->setboardType('M');


this->remarks="Constructor with 2-Parameters (ID,NOC) ";

}

ClassRoom::ClassRoom(int id,int NOC,char c)

{

this->roomID=id;


this->boardType=c;


this->remarks="Constructor with 3-Parameters (ID,NOC,BoardType)

";

}

ClassRoom::ClassRoom(int id,int NOC,char c,string mul)

{

this->setroomID(id); //this->roomID=id;

this->setnumberOfChairs(NOC); //this->numberOfChairs=NOC;

this->setboardType(c); //this->boardType=c;


this->setremarks("Constructor with 4-Parameters

(ID,NOC,BoardType,Multimedia)");

}

ClassRoom::ClassRoom(int id,int NOC,char c,string mul, string remks)

{





this->setremarks(remks+"\nConstructor with All(5)Parameters

(ID,NOC,BoardType,Multimedia,Remarks)");

}

/*

Room ID : 0

N.O. Chairs : 0

Board Type : M

Multimedia : New

Remarks :

Default Constructor

----------------------------------

Room ID : 1

N.O. Chairs : 0

Board Type : M

Multimedia : New

Remarks :

Constructor with 1-Parameter (ID)

----------------------------------

Room ID : 2

N.O. Chairs : 30

Board Type : M

Multimedia : New

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Remarks :

Constructor with 2-Parameters (ID,NOC)

----------------------------------

Room ID : 3

N.O. Chairs : 35

Board Type : M

Multimedia : New

Remarks :

Constructor with 3-Parameters (ID,NOC,BoardType)

----------------------------------

Room ID : 4

N.O. Chairs : 40

Board Type : M


Remarks :

Constructor with 4-Parameters (ID,NOC,BoardType,Multimedia)

----------------------------------

Room ID : 5

N.O. Chairs : 40

Board Type : M


Remarks :



----------------------------------


*/

Constructor with Default Parameters

Given example demonstrates the concept of constructor with default values.

#include

#include


class ClassRoom {

private:

int roomID;

int numberOfChairs;

char boardType; // C for chalk and M for marker

string multimedia;

string remarks;

public:

ClassRoom(int id=0,int NOC=25,char c='C',string mul="New",string

rmks="Defaut Value");

void setroomID(int);

void setnumberOfChairs(int);

void setboardType(char);

void setmultimedia(string);

void setremarks(string);

int getroomID();

int getnumberOfChairs();

char getboardType();

string getmultimedia();

string getremarks();

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void display();

};

void main ()

{

ClassRoom CR0,CR1(1),CR2(2,30),CR3(3,35,'M'),

CR4(4,40,'M',"Repairing.."),CR5(5,40,'M',"Repairing..","Remarks

added from Main");

CR0.display();

CR1.display();

CR2.display();

CR3.display();

CR4.display();

CR5.display();

system("PAUSE");

}

//--------------------------------------Constructor


{





this->setremarks(remks);

}

// All Setter & Getter Functions Deffinitions

//Printing Functions

/*

Room ID : 0

N.O. Chairs : 0

Board Type : M

Multimedia : New

Remarks :

Default Constructor

----------------------------------

Room ID : 1

N.O. Chairs : 0

Board Type : M

Multimedia : New

Remarks :

Constructor with 1-Parameter (ID)

----------------------------------

Room ID : 2

N.O. Chairs : 30

Board Type : M

Multimedia : New

Remarks :

Constructor with 2-Parameters (ID,NOC)

----------------------------------

Room ID : 3

N.O. Chairs : 35

Board Type : M

Multimedia : New

Remarks :

Constructor with 3-Parameters (ID,NOC,BoardType)

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----------------------------------

Room ID : 4

N.O. Chairs : 40

Board Type : M


Remarks :

Constructor with 4-Parameters (ID,NOC,BoardType,Multimedia)

----------------------------------

Room ID : 5

N.O. Chairs : 40

Board Type : M


Remarks :



----------------------------------


*/

#include

#include


class ClassRoom {

private:

//All data members of this calls, for reference see the above example

public:

ClassRoom(int id=0,int NOC=25,char c='C',string mul="New",string

rmks="Defaut Value");

~ClassRoom();

//All setter,getter and prinitng functions prototyping statements (see

above example for reference)

};

void main ()

{

ClassRoom CR0;

{

ClassRoom CR1(1);

{

ClassRoom CR2(2,30);

{

ClassRoom CR3(3,35,'M');

{

ClassRoom CR4(4,40,'M',"Repairing..");

{

ClassRoom

CR5(5,40,'M',"Repairing..","Remarks added from Main");

}

}

}

}

}

system("PAUSE");

}

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//--------------------------------------Constructor


{






}

//--------------------------------------Destructor

ClassRoom::~ClassRoom()

{

cout

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void main ()

{

ClassRoom CR0;

ClassRoom CR1(CR0);

CR0.display();

CR1.display();

CR1.display();

system("PAUSE");

}

//--------------------------------------Constructors


{






}

ClassRoom::ClassRoom(ClassRoom CR)

{

this->roomID=CR.roomID;

this->numberOfChairs=CR.numberOfChairs;

this->boardType=CR.boardType;

this->multimedia=CR.multimedia;

this->remarks=CR.remarks+" Object Created by Copy Constructor";

}

//--------------------------------------Destructors

ClassRoom ClassRoom::copyMe()

{

ClassRoom temp;

temp.roomID=this->roomID;

temp.numberOfChairs=this->numberOfChairs;

temp.boardType=this->boardType;

temp.multimedia=this->multimedia;

temp.remarks=this->remarks+" After Copying Room ";

return temp;

}

//---------------------------------------Setter Functions

void ClassRoom::setroomID(int id)

{

this->roomID=id;

}

void ClassRoom::setnumberOfChairs(int NOC)

{


}

void ClassRoom::setboardType(char c)

{

this->boardType=c;

}

void ClassRoom::setmultimedia(string str)

{

this->multimedia=str;

}

void ClassRoom::setremarks(string str)

{

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this->remarks=str;

}



{


}


{


}


{


}


{


}


{


}



{

cout

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*/

Arrays of Class Objects & Constructors A cat class example which demonstrates that how to create the array of objects.

#include #include using namespace std; class Cat { public: Cat(string name = "tom", string color = "black_and_white") : _name(name), _color(color) {} ~Cat() {} void setName(string name) { _name = name; } string getName() { return _name; } void setColor(string color) { _color = color; } string getColor() { return _color; } void speak() { cout

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morris is orange tom is black_and_white and speaks meow tom is black_and_white and speaks meow tom is black_and_white and speaks meow tom is black_and_white and speaks meow tom is black_and_white and speaks meow Press any key to continue . . . */

#include using namespace std; const int MAX =100; class Details { private: int fscMarks; int rollNumber; public: void inputData( ) { cout > rollNumber; cout > fscMarks; } void printData( ) { cout

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Enter the FSc Marks: 555 Enter another (y/n)?: y Enter the Employee Number # 2 Enter the Roll Number: 222 Enter the FSc Marks: 666 Enter another (y/n)?: y Enter the Employee Number # 3 Enter the Roll Number: 333 Enter the FSc Marks: 777 Enter another (y/n)?: y Enter the Employee Number # 4 Enter the Roll Number: 444 Enter the FSc Marks: 888 Enter another (y/n)?: y Enter the Employee Number # 5 Enter the Roll Number: 555 Enter the FSc Marks: 999 Enter another (y/n)?: n Employee Number is:: 1Student with Roll # :111 have 111 marks in FS. Employee Number is:: 2Student with Roll # :222 have 222 marks in FS. Employee Number is:: 3Student with Roll # :333 have 333 marks in FS. Employee Number is:: 4Student with Roll # :444 have 444 marks in FS. Employee Number is:: 5Student with Roll # :555 have 555 marks in FS. Press any key to continue . . . */