Data Structures using OOP C++ Lecture 1 - الجامعة التكنولوجيةuotechnology.edu.iq/ce/lecture 2013n/2nd-DS_Zainab... · · 2017-01-22Data Structures using OOP C++

Data Structures using OOP C++ Lecture 1

Asst. Lec. Zainab Mahmood Fadhil Page 1

References:

1. E Balagurusamy ,”Object Oriented Programming with C++”, 4th

edition,

McGraw-Hill 2008.

2. Robert Lafore, “Object-Oriented Programming in C++”, 4th

edition, 2002, SAMS publishing.

3. Robert L. Kruse and Alexander J. Ryba, “Data Structures and Program

Design in C++”, Prentice-Hall 2000.

C++ Review

A Simple C++ Program

// welcome.cpp

//

// This program prints

// a welcome message

#include <iostream>

using namespace std;

void main()

{

// print welcome message

cout<<“Welcome to C++ programming“;

}

C++ Program Structure

Comments

Libraries

main function

Statements that define memory locations (constants and

variables)

Statements that specify actions to be taken (i.e. flow of controls)

Operational expressions involving data representations

Representations of data of different types (e.g. structure)

Other Functions and procedures



// Comments

.....

.....

// Comments

Links to Libraries

...... Lib 1

......

...... Lib M

Links to Libraries

Main Program

{

input & initialisation

Expressions, Statements

function calls

output & termination

}

Arrays

An array is a group of consecutive, adjacent memory locations (i.e.

elements) that all have the same data type. Arrays may have from one to

several dimensions. We will study the one-dimensional (1D) and two-

dimensional (2D) arrays.

1D Array

Definition:

data type arrayName[ Size ];

The Size must be an integer constant greater than zero.

For example:

int a[10];

char name[20];

float temperature[6];



For example:

a[3] = 60; // assign 60 to the fourth element

cin >> mark[3]; // read the value of the 4th mark

for(int i=0; i<10; i++)

cin >> a[i]; // input values to the array

for(int j=0; j<10; j++)

cout << a[j]; // print values of the array

Array initialization:

C++ allows the initialization of arrays at the time of their declaration. For

example:

int a[5] = { 8 , 5 , 13 , 2 , 9};

int a[ ] = { 8 , 5 , 13 , 2 , 9};

2D Array (Matrix)

Two-dimensional arrays consist of values arranged in rows and columns.

Definition:

data type arrayName[ RowSize ][ColumnSize];

For example:



int a[3][4];

float b[10][20];

Accessing 2D array elements:

arrayName[RowIndex] [ColumnIndex]

For example:

a[3][4] = 60;

cin >> mark[3][1];

for(int i=0; i<10; i++)

for(int j=0; j<10; j++)

cin >> a[i][j]; // input values to the 2D array

for(int m=0; m<10; m++)

{

for(int n=0; n<10; n++)

cout<< a[m][n]<<”\t”; //print values of 2D array

cout<<endl;

}

2D Array initialization:

int b[2][2] = { {1 , 2} , {3 , 4} };

int a[3][4] = { {1 , 2 , 3 , 4} , {5 , 6 , 7 , 8} ,

{3 , 4 , 1 , 2} };



Example: Write a C++ program that adds two initialized 3×4 matrices A

and B and then stores the result in a matrix C. #include <iostream>


void main()

{

int A[3][4] = { {1, 4, 3, 2},

{5, 6, 7, 8},

{9, 10, 11, 12} };

int B[3][4] = { {3, 4, 3, 1},

{8, 7, 5, 6},

{12, 9, 11, 8} };

int C[3][4];

for (int i=0; i<3; i++)

{

for (int j=0; j<4; j++)

{

C[i][j] = A[i][j] + B[i][j];

cout << C[i][j] << "\t";

}

cout << endl;

}

}

Structures

A structure is a collection of simple variables that have same or different

data types: int, float, and so on. This is unlike the array in which all the

variables must be the same type. The data items in a structure are called

the members of the structure.

In order to use a structure in our C++ programs, we need the following:

1) Defining the structure.

2) Defining a structure variable(s).

3) Accessing and manipulating the members of the structure.

Defining the structure

The general form of a structure definition is:

struct structure_name



{

// Structure members

type variable 1;

type variable 2;

.

.

type variable n;

};

Notes:

The structure definition serves only as a blueprint for the creation

of structure variables.

It does not set aside any space in memory or even name any

variables.

A structure definition is merely a specification for how structure

variables will look when they are defined.

Examples: struct Rectangle

{

float length;

float width;

};

Defining the structure variable

The general form of defining a structure variable is:

structure_name structure_var1 , structure_var2 , … ;

Defining a structure variable reserves space in memory. This memory

space is equal to the total size of all the members of structure.

Examples:

Rectangle rec;

Time time1 , time2;



Person ali , ahmed;

There is another way to define the structure variable in the structure

definition:

struct Rectangle

{

float length;

float width;

} rec;

Accessing and manipulating structure members

Once a structure variable has been defined, its members can be accessed

using the dot operator :

structure_var.member

Examples: rec.length = 10;

time2.seconds++;

cin >> ali.name;

cout << ahmed.age;

Initializing Structure Members

Example: Write a C++ program that computes the shaded area in the

figure below using the structure Rectangle. #include <iostream>

using namespace std

struct Rectangle

{

int length;

int width;

};

void main()

{

int area1 , area2;

Rectangle rect1 = {20 , 10};

Rectangle rect2 = {15 , 7 };

area1 = rect1.length * rect1.width;



area2 = rect2.length * rect2.width;

cout << "The shaded area is "

<< area1 - area2 << endl;

}

Structure Variables Assignment

A structure variable can be assigned to another only when they are of the

same structure type.

Example: #include <iostream >


struct Time

{

int hour;

int minute;

int second;

};

void main()

{

Time time1 = { 10 , 15 , 20 };

Time time2;

time2 = time1; // assign first structure variable

// to the second

cout << "The second time is "

<< time2.hour <<":"<< time2.minute << ":"

<< time2.second << endl;

}

Pointers

Every byte in the computer’s memory has an address. Each program,

when it is loaded into memory, occupies a certain range of these

addresses. That means that every variable and every function in your

program starts at a particular address.



The Address-of Operator &

We can find the address occupied by a variable by using the address-of

operator &.

Example: #include <iostream>

using namespace std; void main()

{

int var1 = 11;

int var2 = 22;

int var3 = 33;

cout << &var1 << endl

<< &var2 << endl

<< &var3 << endl;

}



Output:

0x8fd4fff4

0x8fd4fff2

0x8fd4fff0

Note:

Remember that the address of a variable is not at all the same as its

content. The contents of the three variables are 11, 22, and 33.

Pointer

A pointer is a variable that holds an address value. Hence we can use

pointers to find out where things are in memory. The data type of pointer

is not the same as the variable whose address is being stored; a pointer to

int is not type int.



void main()

{

int var1 = 11;

int var2 = 22;

cout << &var1 << endl

<< &var2 << endl;

int *ptr; // define a pointer to integers

ptr = &var1; // pointer points to var1

cout << ptr << endl; // print pointer value

ptr = &var2; // pointer points to var2

cout << ptr << endl; // print pointer value

}



Another examples: char *cptr; // pointer to char

float *fptr; // pointer to float

Distance *distptr; // pointer to Distance structure

To define more than one pointer of the same type: int *ptr1, *ptr2, *ptr3;

Important Note:

Pointers must have a value. Before a pointer is used, a specific address

must be placed in it. Otherwise it will point to an address we don’t want it

to point to (into our program or operating system). This can cause system

crash since the compiler gives no warning.



Accessing the content of pointer

The content of pointer is the value of the variable pointed to by that

pointer.



void main()

{

int var1 = 11;

int var2 = 22;

int *ptr;

ptr = &var1;

cout<< *ptr <<endl;

ptr = &var2;

cout<< *ptr <<endl;

}


using namespce std;

void main()

{

int var1, var2;

int* ptr;

ptr = &var1;

*ptr = 37; // same as var1=37

var2 = *ptr; // same as var2=var1

cout << var2 << endl;

}

The advantage of using pointers becomes evident when we cannot access

a variable directly, as we will see later.



Uses of pointers

Pointers are an important feature of C++. They are used for:

Accessing array elements

Passing arguments to a function when the function needs to modify

the original argument

Passing arrays and strings to functions

Obtaining memory from the system

Creating data structures such as linked lists

Pointers and Arrays



void main()

{

int a[5] = { 31, 54, 77, 52, 93 };

for(int i=0; i<5; i++)

cout << a[i] << endl;

cout<<endl;

// Or use pointer

for(i=0; i<5; i++)

cout<< *(a+i) << endl;

}



Note:

The name of an array is a pointer constant (i.e. address).

Since we cannot increment or decrement an address, we can increment or

decrement a pointer that holds that address.



void main()

{

int a[5] = { 31, 54, 77, 52, 93 };

int *ptr;

ptr = a; //points to a

for(int j=0; j<5; j++)

cout << *(ptr++) << endl;

}

Documents

Data Structures using OOP C++ Lecture 1 - الجامعة التكنولوجيةuotechnology.edu.iq/ce/lecture 2013n/2nd-DS_Zainab... · · 2017-01-22Data Structures using OOP C++