OOP Lecture 10: Interface-Implementation Separation, Const Member Functions, this Pointer, Slides of Object Oriented Programming

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Object Oriented Programming

(OOP)

Lecture No. 10

Review

Copy constructors

Destructor

Accessor Functions

this Pointer

Example

Student Student::setRollNo(int aNo){

… return *this; } Student Student::setName(char *aName){

… return *this; }

Example

int

main() {

Student

aStudent;

Student

bStudent;

bStudent

=

aStudent.setName(“Ahmad”);

… bStudent

=

aStudent.setName(“Ali”).setRollNo(2);

return

0;

}

Complex Number

There are two representations ofcomplex number^ 

Euler form^ ►

z = x +

i

y

Phasor form^ ►

z = |z| (cos

i

sin

►

z is known as the complex modulusand

is known as the complex

Example

float getX()float getY()void setNumber

(float i, float j) float xfloat y Old implementationComplex

float getX()float getY()void setNumber

(float i, float j) float zfloat theta NewimplementationComplex

Example

class Complex{ //new

float z;float theta; public:

void setNumber(float i, float j){

theta = arctan(j/i);…

} … };

Advantages

User is only concerned about waysof accessing data (interface)

User has no concern about theinternal representation andimplementation of the class

Student.h

class Student{

int rollNo; public:

void setRollNo(int aRollNo);int getRollNo();… };

Student.cpp

#include “student.h”void Student::setRollNo(int aNo){

} int Student::getRollNo(){… }

There are functions that aremeant to be read only

There must exist a mechanismto detect error if such functionsaccidentally change the datamember

const

Member Functions

Keyword

const

is placed at the

end of the parameter list

const

Member Functions

Example

class

Student{

public:

int

getRollNo()

const{

return

rollNo;

const

Functions

Constant member functions cannotmodify the state of any object

They are just

“read-only”

Errors due to typing are alsocaught at compile time