Looking inside an Array

Linear search is simplest searching algorithm to find an element in an array. This example has an array with  6 elements. A key is value that we are looking for inside of an array, and we are looking for value 4. Another integer variable index is used for storing index value of element that has matching value as the key value. We initialize index with arr.length, which it return the size of the array.

Out search engine build using for loop. This engine will check all the elements in the array one by one. The if statement inside the loop is where it checks whether value of arr at current location indicated by variable i is same as value of key. If the values are equal we change the index value to value of i.

Third part is displaying results. If the value of index not equal to arr.length, that means something has happen inside the loop statement. This something can happen only and only if key is found inside the array. So this if statement actually checks whether the key is found or not. Thus, if the key is found it display key is found at which index position or else key not found message is displayed.

The Java Code:


public class LinearSearch {

   public static void main(String[] args) {
     int arr[] = {2,3,1,4,6,8};   // the array that we want to look into
     int key = 4;                        // number to search for
     int index = arr.length;      // variable to keep index number
    
     // the search engine
     for(int i=0;i<arr.length;i++){
        if(arr[i] == key){
           index = i;
        }
     }
    
     //display result
     if(index != arr.length){
        System.out.println("Number " + key + " is found at index " + index);
     }else{
        System.out.println("Number " + key + " is not found");
     }
   }
}

Output:

case 1: if key is found

In this case the value given to this program is 4, which suppose to be found by the program inside the array. The index value is 3 because all array starts from index value 0.

Number 4 is found at index 3

case 2: if key not found

The second case happens if the key value given is not in the array. The value of index will  remain unchanged for this case.

Number 7 is not found

Next, we will look into improved version of search engine. 

Comments

Post a Comment

Popular posts from this blog

Drawing Simple Pie Chart

Image
To draw pie chart with 5 sectors. The program calculates the total of all the input given by user and find the angle in degrees to draw each sectors. When the program first loads, chart based on default values is painted by the program. User can edit the values in the text field and presses draw button to redraw the chart. Each time the draw button is pressed, new set of angle is calculated and repainted. I have attached the the sources for this program. It is simple and needs upgrades. Pie.java This class executed the program and initializes the components JTextField and JPanel to draw the chart. package coolApp.graphics; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Pie { JTextField a,b,c,d,e; JButton btnDraw; double total; JPanel contentPane; Pie(){ JFrame frame = new JFrame("Pie - CoolApps"); frame.setSize(500,500); contentPane = new JPanel(); contentPane.setLayout(new BorderLayout()); frame
Read more

VB.net connecting to SQL Server

Connecting to SQL server 2014 from VB.Net 2017, read values from the database and display the data in windows form. Before begin to write this program, first we need to import SqlClient class. Imports System.Data.SqlClient Step 1 Create a sql connection object. This is to make connection to object. Dim conn As New SqlConnection() Step 2 Set the connection string to the sqlconnection object: conn.ConnectionString = connStr Road block The variable connStr is a connection string. Connection object need connection string to make connection to database. It has information like who providing the database, the name of the database and some security information. Dim connStr As String = "Data Source = ServerInstanceName;Initial Catalog=testDB;Integrated Security=True" Let's break down the connection string into the three main components. Dim provider As String = "ServerInstanceName;" Dim database As String = "Initial Catalog=testDB;" Dim
Read more

VB.net

a quick and convenient way to build a window based application. basically there is two main components in VB, the design view where we place the controls on a window form. then we have the code view where we write implementation for each controls on the form. Typically the control implementation or procedures are executed when certain events happens to the controls. Events like mouse click, or value change on text box, form load, form close and so on. After working with programming language like C, C++ and Java, getting use to VB is a bit challenging. its because first of all, VB don't use curly bracket to specify code blocks, and the statements don't end with semicolon. variable declaration for example is written as dim age As Integer in C, C++ and Java it written int age; in VB, variable declaration start with dim keyword, it means dimension and the functions are written as Function addNumber(ByVal num1 As Integer, ByVal num2 As Integer) As Integer addNumber
Read more