Chapter 4, Problem 1E

Write a fragment of code that will read words from the keyboard until the word done is entered. For each word except done, report whether its first character is equal to its last character. For the required loop, use a

1. a. while statement
2. b. do-while statement

Explanation of Solution

a.

Using “while” statement:

The code fragment to read words until the user enters “done”. For every word, the program should check whether the first and last characters are match or not. The program using “while” condition is as follows. Code fragment is highlighted.

//Import required package

import java.util.Scanner;

//Define the Main class

public class Main

{

    //Define main method

    public static void main(String[] args)

    {

        //Create an object for scanner class

        Scanner sc = new Scanner(System.in);

        //Declare a variable

        String word = " ";

        //Do till the user enters "done"

        while(!word.equals("done"))

        {

            //Get a word from the user

            System.out.print("\nEnter a word: ");

            word = sc.next();

            //Check if word is equal to "done"

            if(word.equals("done"))

                //Break the loop

                break;

     //Check if 1st and last characters are equal

     if(word.charAt(0) == word.charAt(word.length()-1))

                //Print the message

        System.out.println("The first and last character matches in '"+ word + "'");

            //Else

            else

                //Print the message

        System.out.println("The first and last character does not matches in '"+ word + "'");

        }

    }

}

Explanation:

• The statements under the condition “while(!word.equals("done"))”  gets executed till the user enters “done”.
  • The program then gets a word from the user and then it checks whether the 1^st and last characters are match or not.
  • The program gets halted if the user enters “done”.

Sample Output

Output:

Enter a word: abi

The first and last character does not matches in 'abi'

Enter a word: aruna

The first and last character matches in 'aruna'

Enter a word: done

Explanation of Solution

b.

Using “do-while” statement:

The code fragment to read words until the user enters “done”. For every word, the program should check whether the first and last character are match or not. The program using “do-while” condition is as follows. Code fragment is highlighted.

//Import required package

import java.util.Scanner;

//Define the Main class

public class Main

{

    //Define main method

    public static void main(String[] args)

    {

        //Create an object for scanner class

        Scanner sc = new Scanner(System.in);

        //Declare a variable

        String word = " ";

        //Do till the user enters "done"

        do

        {

            //Get a word from the user

            System.out.print("\nEnter a word: ");

            word = sc.next();

            //Check if word is equal to "done"

            if(word.equals("done"))

                //Break the loop

                break;

     //Check if 1st and last characters are equal

     if(word.charAt(0) == word.charAt(word.length()-1))

                //Print the message

        System.out.println("The first and last character matches in '"+ word + "'");

            //Else

            else

                //Print the message

        System.out.println("The first and last character does not matches in '"+ word + "'");

        } while(!word.equals("done"));

    }

}

Explanation:

• The statements inside “do-while” condition gets executed till the user enters “done”.
  • The program then gets a word from the user and then it checks whether the 1^st and last characters are match or not.
  • The program gets halted if the user enters “done”.

Sample Output

Output:

Enter a word: charles

The first and last character does not matches in 'charles'

Enter a word: david

The first and last character matches in 'david'

Enter a word: done