Data Structure and Algorithm: CIT231

1. Data Structure and Algorithm: CIT231 Lecture 4: ADT and Introduction to Object Oriented Programming (OOP) DeSiaMore www.desiamore.com/ifm www.desiamore.com/ifm

2. Introduction to Object Oriented Programming • In this lecture you will learn the general concepts of Object Oriented Programming (OOP). • Inheritance • Encapsulation • Polymorphism • Object Oriented Programming is very powerful and important programming paradigm. www.desiamore.com/ifm

3. Introduction to Object Oriented Programming • Most of the nowadays sophisticated application software have been developed in Objected Oriented languages and mostly in C++. • E.g. Word processors, spreadsheets, and graphics applications. • Also some Operating Systems are written in OO languages. www.desiamore.com/ifm

4. Fundamental terms and Principles of the OOP • Attribute – The data for a class that maintains the current state of an object. The state of an object is determined by the current contents of all the attributes. • Object – An object is a something that exists and is identifiable. An object exhibits behaviour and maintains state. Example of objects are telephones, automobiles, buildings, animals, etc. www.desiamore.com/ifm

5. Fundamental terms and Principles of the OOP • Class – Class is a synonymous with type. A class specifies a traits (data) and behaviour that an object can exhibit. • A class itself does not exists. It is only a description of an object. A blueprint is analogous to a class and building itself is the object. • A class can be considered a template for the creation of objects. www.desiamore.com/ifm

6. Fundamental terms and Principles of the OOP • Inheritance – This is the relationship of classes. There is an explicit is-a relationship between classes. For example an automobile is-a vehicle, a zebra is-a mammal, a flower is-a plant, and so on. • Interface – The visible functionality of a class. Is the contract an object makes with users of an object. Users manipulate an object through its interface. www.desiamore.com/ifm

7. Fundamental terms and Principles of the OOP • Interface of a class is the part the clients see. An interface is considered a contract the class has with its client. • For example an automobile has an interface (contract) with its driver. An automobile’s interface includes a steering wheel, brake pedals, speedometer, and a clutch. • This interface provides functionality to the driver without the need to know the inner workings of the automobile. www.desiamore.com/ifm

8. Fundamental terms and Principles of the OOP • Implementation – The internal functionality and attributes of a class. A class’s implementation is hidden from users of the class. • Encapsulation – Encompasses the interfaces and abstraction of a class. • Abstraction – The generalisation of a class that distinguish it from other classes www.desiamore.com/ifm

9. Fundamental terms and Principles of the OOP • Understanding inheritance is a good starting point of learning object orientation. • The concept of inheritance can be understood in analog to your family tree. • The procedure to describe your family tree is the same to describe class inheritance in C++. www.desiamore.com/ifm

10. Fundamental terms and Principles of the OOP • Inheritance is known as an is-a relationship. Example a toyota is-a vehicle, a snake is-a reptile, and a flower is-a plant. • To begin applying inheritance, you must decide a base class that must reside within your application. It provides basic, default functionality to users of the class. www.desiamore.com/ifm

11. Access Specifier of the class • The class in C++ contains three important access specifiers which provide conditions to access to the data members and functions (methods) of the class. • These are • Public • Private • Protected www.desiamore.com/ifm

12. Access Specifier of the class • Public – A class member with public visibility is accessible outside of the class. • Private – A class member with private visibility can only be accessible by member functions of the class. • Protected – A class member with protected visibility is accessible by member functions of the class and its descendents. www.desiamore.com/ifm

13. MATRIX Operation with the use of Class • #include <iostream.h> • Const int MAX = 3; • Class Matrix • { • Private: • Int mat[MAX][MAX]; • Public: • Matrix(); • void create (); • void display (); • }; www.desiamore.com/ifm

14. Initialise Matrix() Matrix::Matrix() { for(int i=0; i<MAX; i++) { for (int j=0; j<MAX; j++) mat[i][j]=0; } } www.desiamore.com/ifm

15. Create matrix() //Create matrix mat Void Matrix::create() { int n; for (int i=0; i<MAX; i++) { for (int j = 0; j<MAX; j++) { cout<<“Enter the element: ”; cin>>n; mat[i][j] = n; } } } www.desiamore.com/ifm

16. Display matrix() //displays the contents of the matrix Void Matrix::display(); { for (int i=0; i<MAX; i++) { for (int j=0; j<MAX; j++) cout<<mat[i][j]<<“ ”; cout<<endl; } } www.desiamore.com/ifm

17. Create the object of Matrix in the Main program void main() { matrix mat1; cout<<"\nEnter the elements of the array: \n"; mat1.create(); cout<<"Your array is:\n"; mat1.display(); } www.desiamore.com/ifm

18. Pointers • A pointer is a variable which stores the address of another variable. • There are two important operators when working with pointers in C++: • the address of (&) operator • the value of (*) operator • How much storage space does a pointer consume? Use sizeof(ptr) without the '*‘ operator to determine the memory utilised on your system www.desiamore.com/ifm

19. Pointers • Irrespective of datatype or whether the pointer points to a single variable or array, as a general rule, pointers must use the same amount of memory space. • The & operator gives us the address of a variable and * gives us the value of a variable at a specified address. Example:- www.desiamore.com/ifm

20. Example of the use of * and & • #include <iostream.h> • #include <stdlib.h> • int main() • { • int i = 10; • cout << "The value of variable i is " << i << "\n"; • cout << "The memory address of i is " << &i << "\n"; • /* • Prints the memory address in hexadecimal format • */ • cout << "The value of variable i using * operator is "<< *(&i) <<"\n"; • /* • The * operator gives the value when provided with a memory address. Note • that the dsta type is inferred from the variable name. • */ • system("PAUSE"); • return 0; • } www.desiamore.com/ifm

21. Pointer Example • #include <iostream.h> • #include <stdlib.h> • int main() • { • int i = 10; • int *x = &i; • int *y; • /* • x stores the address of variable i. Pointer assignment could also be done as • */ • y = &i; • cout <<"The pointer x is stored at the mempory address "<< &x << "\n"; • cout <<"The pointer x stores the memory address of i: " << y << "\n"; • /* • Contrast the difference between the memory address of the pointer • and the memory address it stores. • */ • cout<< "The value of i accessed through pointer x is " << *x << "\n"; • /* • Now we manipulate the value of i using pointer x; • */ • *x = *x + 1; // increment i by 1 • cout<< "i (through pointer) = " << *x << " which equals i (direct access) " << i << "\n"; • /* • A pointer does not create a copy of the variable it points to. • */ • cout<<"The memory allocated to the pointer x is " << sizeof(x) << " bytes. "; • system("pause"); • return 0; • } www.desiamore.com/ifm

22. Array as Pointers • In C++ array starts at position 0. • The elements of the array occupy adjacent locations in memory. • C++ treats the name of the array as if it was the pointer to the first element. • If v is an array, *v is the same thing as v[0], *(v+1) is the same thing as v[1] as diagram below shows: www.desiamore.com/ifm

23. Array as Pointers • Pointer use for an array www.desiamore.com/ifm

24. Exercise • Using matrix arrays, write a program to create two matrices and then create methods of adding and subtracting those matrices. www.desiamore.com/ifm

25. Next Topic • String ADT and array of characters www.desiamore.com/ifm