part i chapter 16 cs116 senem kumova metİn 1. structures structures : aggregate data types built...

PART ICHAPTER 16

CS116 SENEM KUMOVA METİN 1

StructuresStructures : Aggregate data types built using elements of

other types

struct Time { int hour; int minute; };

Members of the same structure must have unique names

Two different structures may contain members of the same name

struct st1{ int n; };struct st2{ float n; };

Each structure definition must end with a semicolon


Creating Objects from A Structure in C++struct Time {

int hour; int minute;

};

/*1*/ Time timeObject;

/*2*/ Time timeArray[ 10 ];

/*3*/ Time *timePtr1;

timePtr1= &timeobject;

/*4*/ Time *timePtr2;timePtr2=new Time;

/*5*/ Time &timeRef= timeObject;


Accessing Members of Structures Member access operators:

Dot operator (.) for structures and objects Arrow operator (->) for pointers

Print member hour of timeObject: Time timeObject;Time & timeRef= timeObject;cout << timeObject.hour;cout << timeRef.hour;

OR

Time * timePtr;timePtr = &timeObject; cout << timePtr->hour;

// timePtr->hour is the same as ( *timePtr ).hour


EXAMPLE: Structure#include <iostream>#include<iomanip>using namespace std; struct Time { int hour; // 0-23

int minute; // 0-59 };

void print(const Time & );

int main() {

Time dinnerTime; dinnerTime.hour = 18; dinnerTime.minute= 30; cout<<endl;

print( dinnerTime ); }


void print( const Time &t ) { cout

<<setfill(‘0’)<<setw(2)<<t.hour<<“:”<< setw(2)<<t.minute ;

}

STRUCTURES : No Information Hidingstruct Time { int hour; int minute; };

Time x;x.hour=23; x.minute =54;

All members of the structure are accessible!!

All members are public

NO INFORMATION HIDING


CLASSESA class is a data type

Model objects that have bothattributes (data members) behaviors (member functions -methods)

Have a body delineated with braces ({ and })

Class definitions terminate with a semicolon

class Time { /* data members and methods */};


class tagkeyword

Creating objects from classesclass Time { // data members and methods

…… };

/*1*/ Time dinnertime; // Creates an object of type Time

/*2*/ Time array[ 5 ]; // array of Time objects

/*3*/ Time *pointer1; // pointer to a Time object pointer1=&dinnertime;

/*4*/ Time *pointer2= new Time; // pointer to a Time object

/*5*/ Time &dinnerTime = dinnertime; // reference to a Time object


Information Hiding in C++ In C ++ classes can limit the access to their members and

methods

The three types of access a class can grant are:

public : this keyword can be used to expose data members and methods (make accessible wherever the program has access to an object of the class )

private : this keyword can be used to hide data members and methods (make accessible only to member methods of the class )

protected : Similar to private ( will study it later!!) CS116 SENEM KUMOVA METİN 9

Class Declaration class Time {

public: void setTime( int, int ); // sets hour,minute public: void print(); // prints timeprivate: int hour; // 0 – 23 int minute; // 0 – 59

};

// Time class consists of public methods and private data members// A colon : follows the keywords private and public


const keywordclass Time {

public: void setTime( int, int); // sets hour,minute void print() const; // prints time

private: int hour; // 0 – 23 int minute; // 0 – 59

};

/* The keyword const in methods “print” shows that unlike method SetTime, these methods do not change the value of any Time data member…

*/


Member selector operator Access to any class member, whether data member or method, is

supported by the member selector operator “.” and the class indirection operator “->”

class Time {

public: void setTime( int h, int m); // sets hour,minute void print() const; // prints time private: int hour; // 0 – 23 int minute; // 0 – 59

};

main(){

Time noww; // declare an object from class Time noww.setTime (11,30);

noww.minute =34; // IS it possible ?????}


Class Scopeclass C{ public : void m(); // public scope

private :char d; // private scope == class scopeint f();

};

// If no public and private keywords are used then the members are default in private scope

class D{ int x; } ;

equals to

class D{ private : int x; };


Defining Class Methods

1.A method can be defined inside the class declaration. Such a definition is said to be “inline”

2.A method can be declared inside the class declaration but can be defined outside the class declaration


Defining Class Methods 1class Person {

public : void setAge (int n) { age = n; }; // inline definition int getAge() const {return age};

private:int age;

};


Defining Class Methods 2class Person {

public : void setAge (int n); // declares the method int getAge() const;

private:int age;

};

// definitions for methods

void Person :: setAge(int n){ age = n; }

int Person :: getAge() const { return age; }


Using Classes in a Program#include<iostream>using namespace std;

class Person { public :

void setAge (int n) { age = n; }; int getAge() const {return age;};

private:int age;};

void main(){ Person p;

p.setAge(12);cout <<p.getAge()<<endl; // p.age=13; ???????

Person student [2];student[0].setAge(12); student[1].setAge(15);

for (int i=0; i<2;i++)cout<<student[i].getAge()<<endl; }


Initializing Class Objects: Constructors Method that initializes class members

Same name as the class

No return type

Member variables can be initialized by the constructor or set afterwards


Constructors : inline definition class Person {

public : Person() { age =0; name =“Unknown”; }

void setAge (int n) { age =n };

int getAge() const { return age };

void getName() const { cout <<name<<endl; }

private:int age;string name;

};


cout <<p.getAge()<<endl; cout <<p.getName()<<endl; }


Constructors class Person {

public : Person() ;

void setAge (int n) { age =n };

int getAge() const { return age };

void getName() const { cout <<name<<endl; }private:

int age;string name;

};

Person ::Person() { age =0;

name =“Unknown”; }


cout <<p.getAge()<<endl; cout <<p.getName()<<endl; }


Constructors : Overloadingclass Person {

public :

Person() { age =0; name =“Unknown”; } // First Constructor

Person( const string & n) { name =n; } // Second Constructor

void setAge (int n) { age =n; }; int getAge() const { return age };void getName() const { cout <<name<<endl; }

private:int age;string name; };

void main(){ Person q; // USING FIRST CONSTRUCTOR

cout <<q.getAge()<<endl;cout<< q.getName()<<endl

Person p(“David”); // USING SECOND CONSTRUCTORcout <<p.getAge()<<endl; cout <<p.getName()<<endl;

}


AN EXAMPLE FROM YOUR TEXT BOOK#include<iostream>#include<string>using namespace std;

class GradeBook {

private: string courseName;public :

void setcourseName (string n) { courseName=n; }

string getcourseName() { return courseName;}

GradeBook(string name) { setcourseName(name);}

void displayMessage(){ cout<<“Welcome”<<getcourseName(); }

};

void main(){

GradeBook book1(“CS116 Int. To Programming II”);cout <<book1.getcourseName()<<endl; }


AN EXAMPLE FROM YOUR TEXT BOOK//GradeBook.h#include<iostream>#include<string>

using namespace std;

class GradeBook {

private: string courseName;public :

void setcourseName (string n) { courseName=n; }

string getcourseName() { return courseName;}

GradeBook(string name) { setcourseName(name);}

void displayMessage()

{ cout<<“Welcome”<<getcourseName(); } };


#include<iostream>#include “GradeBook.h”

using namespace std; void main() {

GradeBook book1(“CS116”);cout <<book1.getcourseName()<<endl;

}

part i chapter 16 cs116 senem kumova metİn 1. structures structures : aggregate data types built...

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