Chapter 4, Problem 1RE

Given the variables

 String stars = "*****";

 String stripes = =====;

what do these loops print?

1. a. int i = 0;

  while (i < 5)

  {

 System.out.println(stars.substring(0, i));

   i++;

}

1. b. int i = 0;

   while (i < 5)

   {

    System.out.print(stars.substrings (0, i));

    System.out.println(stripes.substrings(i, 5));

    i++;

   }

2. c. int i = 0;

   while (i < 10)

   {

    if (i % 2 == 0) { System.out.println(stars); }

    else { System.out.println(stripes); }

   }

Explanation of Solution

a.

//Definition of class Test

class Test

{

    //Definition of method main

    public static void main(String[] args)

    {

        //Initialize the variables

        String stars = "*****";

        String stripes = "=====";

        //Initialize the value of "i" to 0

        int i = 0;

        //Check the condition using while loop

        while (i < 5)

        {

            //Print the output

System.out.println(stars.substring(0, i));

            //Increment the value of "i"

            i++;

        }

    }

}

Explanation:

The above code snippet initializes the variable “i” to “0”. The condition “i<=5” is checked using “while” loop. Print the output and increment the value of “i”.

Sample Output

Output:

*

**

***

****

Explanation of Solution

b.

//Definition of class Test

class Test

{

    //Definition of method main

    public static void main(String[] args)

    {

        //Initialize the variables

        String stars = "*****";

        String stripes = "=====";

        //Initialize the value of "i" to 0

        int i = 0;

        //Check the condition using while loop

        while (i < 5)

        {

            //Print the output

System.out.println(stars.substring(0, i));

//Print the output

System.out.println(stars.substring(i, 5));

            //Increment the value of "i"

i++;

        }

    }

}

Explanation:

The above code snippet initializes the variable “i” to “0”. The condition “i<=5” is checked using “while” loop. Print the output by calling the two sub string function and increment the value of “i”.

Sample Output

Output:

*****

*

****

**

***

***

**

****

*

Explanation of Solution

c.

//Definition of class Main

class Main

{

    //Definition of method main

    public static void main(String[] args)

    {

           //Initialize the variables

        String stars = "*****";

        String stripes = "=====";

        //Initialize the value of "i" to 0

        int i = 0;

        //Check the condition using while loop

        while (i < 10)

        {

//Check the condition for "i%2" equals to 0

            if (i % 2 == 0)

            {

                //Print the output

                System.out.println(stars);

            }

            else

            {

                //Print the output

                System.out.println(stripes);

            }

        }

    }

}

Explanation:

The above code snippet initializes the variable “i” to “0”. The condition “i<=10” is checked using “while” loop. Inside the while loop, check the condition of “i%2” using the “if” statement.

Sample Output

Output:

*****

*****

*****

*****

*****

*****

*****

.

.

.

.

Infinite loop