CPCS204 Data Structures 1 1433/1434H Lab

Lab Manual

CPCS204

Data Structures 1

Department of Computer Science

1433/1434H

Lab - 2

Learning Procedure

1) Stage J (Journey

inside-out the concept

) 2) Stage a

1

(apply

the learned

)

3) Stage v (verify

the accuracy

)

4) Stage a

2

(assess

^{your work}

)

Laboratory 2:

Statement Purpose:

This lab will give you an overview of Array Concepts and Principles.

Activity Outcomes:

This lab teaches you the following topics:

 The basics of one-dimensional and 2-dimensional arrays.

 Review of defining and handling array structure and elements.

 Practicing the use of arrays in programming.

 Employing arrays in some programming solutions.

Instructor Note:

As pre-lab activity, review Ch2, from the book Data Structures with Java by John R. Hubbard and also the relevant instructor’s slides.

Names I.D.

1. .………..………. ………

2. ..……….. ………

3. .………... ………

4. .……….. ..……….

CPCS204 – The Lab Note Lab-2

1) Stage J (Journey)

A. One-Dimensional Arrays:

Array Basics

 An array is used to store a collection of similar data type under one name.

 Instead of declaring individual variables, such as number0, number1, ..., and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and ..., numbers[99] to represent individual variables.

 Declaring Array Variables

dataType[] arrayRefVar;

double[] myList;

Creating Arrays



arrayRefVar = new dataType[arraySize];

OR



dataType[] arrayRefVar = new dataType[arraySize];

for example,

double[] myList = new double[10];

B. Two-Dimensional Arrays:

Thus far, you have used one-dimensional arrays to model linear collections of elements.

You can use a two-dimensional array to represent a matrix or a table.

Creating Two-Dimensional Arrays and Declaring its Variables Here is the syntax for declaring a two-dimensional array:

dataType[][] arrayRefVar;

As an example, here is how you would declare a two-dimensional array variable matrix of int values:

int[][] matrix;

You can create a two-dimensional array of 5 by 5 int values and assign it to matrix using this syntax:

matrix = new int[5][5];

2) Stage a

1

(apply)

Example 1:

CPCS204 – The Lab Note Lab-2

import javax.swing.JOptionPane;

public class TestArray { /** Main method */

public static void main(String[] args) { final int TOTAL NUMBERS = 6;

int[] numbers = new int[TOTAL NUMBERS

];

// Read all numbers

for (int i = 0; i < numbers.length; i++) { String numString =

JOptionPane.showInputDialog("Enter a number:");

// Convert string into integer

numbers[i] = Integer.parseInt(numString);

}

// Find the largest int max = numbers[0];

for (int i = 1; i < numbers.length; i++) { if (max < numbers[i]) {

max = numbers[i];

} }

// Find the occurrence of the largest number int count = 0;

for (int i = 0; i < numbers.length; i++) { if (numbers[i] == max) {

count++;

} }

// Prepare the result

String output = "The array is ";

for (int i = 0; i < numbers.length; i++) { output += numbers[i] + " ";

}

output += "\nThe largest number is " + max;

output += "\nThe occurrence count of the largest number " + "is " + count;

// Display the result

JOptionPane.showMessageDialog(null, output);

} }

Example 2: Assigning Grades

This example writes a program that reads student scores, gets the best score, and then assigns grades based on the following scheme:

Grade is A if score is > = - 10;

Grade is B if score is > = - 20;

Grade is C if score is > = - 30;

Grade is D if score is > = - 40;

Grade is F otherwise.

The program prompts the user to enter the total number of students, then prompts the user to enter all of the scores, and concludes by displaying the grades.

import javax.swing.JOptionPane;

public class AssignGrade { /** Main method */

public static void main(String[] args) { // Get number of students

String numberOfStudentsString =

JOptionPane.showInputDialog("Please enter number of students:");

// Convert string into integer int numberOfStudents =

Integer.parseInt(numberOfStudentsString);

int[] scores = new int[numberOfStudents];

// Array scores

int best = 0;

// The best score char grade;

CPCS204 – The Lab Note Lab-2

// The grade

// Read scores and find the best score for (int i = 0; i < scores.length; i++) { String scoreString =

JOptionPane.showInputDialog("Please enter a score:");

// Convert string into integer

scores[i] = Integer.parseInt(scoreString);

if (scores[i] > best) { best = scores[i];

} }

// Declare and initialize output string String output = "";

// Assign and display grades

for (int i = 0; i < scores.length; i++) { if (scores[i] >= best - 10) {

grade = 'A';

} else if (scores[i] >= best - 20) { grade = 'B';

} else if (scores[i] >= best - 30) { grade = 'C';

} else if (scores[i] >= best - 40) { grade = 'D';

} else {

grade = 'F';

}

output += "Student " + i + " score is " + scores[i] + " and grade is " + grade + "\n";

}

// Display the result

JOptionPane.showMessageDialog(null, output);

} }

Example 3:

public class GradeExam { /** Main method */

public static void main(String args[]) { // Students' answers to the questions char[][] answers = {

{'A', 'B', 'A', 'C', 'C', 'D', 'E', 'E', 'A', 'D'},

{'D', 'B', 'A', 'B', 'C', 'A', 'E', 'E', 'A', 'D'},

{'E', 'D', 'D', 'A', 'C', 'B', 'E', 'E', 'A', 'D'},

{'C', 'B', 'A', 'E', 'D', 'C', 'E', 'E', 'A', 'D'},

{'A', 'B', 'D', 'C', 'C', 'D', 'E', 'E', 'A', 'D'},

{'B', 'B', 'E', 'C', 'C', 'D', 'E', 'E', 'A', 'D'},

{'B', 'B', 'A', 'C', 'C', 'D', 'E', 'E', 'A', 'D'},

{'E', 'B', 'E', 'C', 'C', 'D', 'E', 'E', 'A', 'D'}};

// Key to the questions

char[] keys = {'D', 'B', 'D', 'C', 'C', 'D', 'A', 'E', 'A', 'D'};

// Grade all answers

for (int i = 0; i < answers.length; i++) { // Grade one student

CPCS204 – The Lab Note Lab-2

int correctCount = 0;

for (int j = 0; j < answers[i].length; j++) { if (answers[i][j] == keys[j]) {

correctCount++;

} }

System.out.println("Student " + i + "'s correct count is " + correctCount);

} } }

Task 1:

NOW after compiling and running this example code in Netbeans IDE, try to run the

GradeExam.class

and

projectName.jar

code file using CMD (i.e.

commend line program under windows OS) where the result should be as follows:

3) Stage v (verify)

Programming Exercises

Ex-1: Find and correct the error in each of the following program segments:

1.final int ARRAY_SIZE = 5; ARRAY_SIZE = 10;

2.

Assume

int b[] = new int [ 10 ]; for ( int i = 0; i <=

b.length; i++ ) b[ i ] = 1;

Assume

Ex-2: Consider a two-by-three (integer) array t.

1. Write a statement that declares and creates t.

2. How many rows does t have?

3. How many columns does t have?

4. How many elements does t have?

5. Write the names of all the elements in the second row of t.

6. Write the names of all the elements in the third column of t.

7. Write a single statement that sets the element of t in row 1 and column 2 to value of 5.

8. Write a nested for statement that initializes each element of t to value of 1.

9. Write a nested for statement that inputs the values for the elements of t from the user.

10.Write a statement that displays the elements of the first row of t.

11.Write a statement that totals the elements of the third column of t.

12.Define a method called printArray(int [][] arr)that receive two-by-three integer array and print its elements such that:

If arr={{1,2,3},{4,5,6}};

The output of printing ---

1 2 3 4 5 6

---

13.Use

printArray()

Use method to print t array after the steps (1, 7, 8, and 9).

CPCS204 – The Lab Note Lab-2

Ex-3:

1. Write a program that reads ten numbers, computes their average, and finds out how many numbers are above the average.

2. Write a program that reads ten integers and displays them in the reverse of the order in which they were read.

3. Write a program that reads ten numbers and prints the Maximum and Minimum number among the entered ten numbers.

4. Write a program that sums all the integers in the major diagonal in a matrix of integers. Use {{1, 2, 4, 5}, {6, 7, 8, 9}, {10, 11, 12, 13}, {14, 15, 16, 17}} to test the method.

4) Stage a

2

(assess) Lab Work:

In each laboratory you are assessed on your work within lab session based on your participation, discussions and achievement of lab activities. Thus, each lab has a portion of the (LAB WORK MARK). Therefore, a checklist of each lab is used to evaluate your work. This checklist accounts the following criteria:

 Following the lab manual step by step

 Answering given questions concisely and precisely

 Practicing and implementing given examples correctly

 Writing code of required programming tasks

 Being focused, positive, interactive and serious during lab session

 Asking good questions or answering instructor questions if any

Note: performing given home activities or extra programming is highly

recommended to improve your understanding, capability and programming

skills.