Sentinel Controlled While Loop

Submitted by GeePee on Tuesday, May 19, 2015 - 22:48.

The following java program application uses Sentinel Controlled While Loop. You might not know how many times a set of statements need to be executed, but you do know that the statements need to be executed until a special value is met. This special value is called a sentinel. . I will be using the JCreator IDE in developing the program. To start in this tutorial, first open the JCreator IDE, click new and paste the following code:

import java.util.*;
 
public class SentinelControlledWhileLoop
{
        static Scanner console = new Scanner(System.in);
        
        static final int SENTINEL = -999;
        
        public static void main (String[] args)
        {
                int number; //variable to store the number
                int sum = 0; //variable to store the sum
                int count = 0; //variable to store the total numbers read
                
                System.out.println("Enter positive integers ending with " + SENTINEL);
                
                number = console.nextInt();
                
                while (number != SENTINEL)
                {
                        sum = sum+number;
                        count++;
                        number = console.nextInt();
                }
                System.out.printf("the sum of the %d " +
                        "numbers = %d%n", count, sum);
                if (count != 0)
                        System.out.printf("The average = %d%n", (sum / count));
                else
                        System.out.println("No input");
        }
}

Sample Run:


Enter positive integers ending with -999
10 
19
-999
The sum of the 2 numbers = 19
The average = 9

This program works as follows: The statement System.out.println("Enter positive integers ending with " + SENTINEL);prompts the user to enter numbers ending with -999. The statement number = console.nextInt();reads the first number and stores it in the variable number. The while statement while (number != SENTINEL)checks whether number is not equal to SENTINEL. If number is not equal to SENTINEL, the body of the while loop executes. The statement sum = sum+number;updates the value of sum by adding number to it. The statement count++; increments the value of count by 1. The statement number = console.nextInt();stores the next number in the variable number. The statements

 sum = sum+number;
                        count++;
                        number = console.nextInt();

repeats until the programs reads -999. The statement

 System.out.printf("the sum of the %d " +
                        "numbers = %d%n", count, sum);

outputs the sum of the numbers, and the statements

 if (count != 0)
                        System.out.printf("The average = %d%n", (sum / count));
                else
                        System.out.println("No input"); 

output the average of the numbers.

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