JavaScript/JScript: Control Structures I - Pearson Learning Solutions

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Chapter 14 JavaScript/JScript: Control Structures I 443
14.23 Write a script that reads in the size of the side of a square and outputs HTML text that displays
a hollow square of that size out of asterisks. Use a prompt dialog to read the size from the user.
Your program should work for squares of all side sizes between 1 and 20.
14.24 A palindrome is a number or a text phrase that reads the same backward as forward. For example,
each of the following five-digit integers is a palindrome: 12321, 55555, 45554 and 11611.
Write a script that reads in a five-digit integer and determines whether it is a palindrome. If the number
is not five digits, output HTML text that displays an alert dialog indicating the problem to the
user. When the user dismisses the alert dialog, allow the user to enter a new value.
14.25 Write a script that outputs HTML text that displays the following checkerboard pattern:
* * * * * * * *
* * * * * * * *
* * * * * * * *
* * * * * * * *
* * * * * * * *
* * * * * * * *
* * * * * * * *
* * * * * * * *
Your program may use only three output statements, one of the form
one of the form
document.write( "* " );
document.write( " " );
and one of the form
document.writeln( "" );
[Hint: Repetition structures are required in this exercise.]
14.26 Write a script that outputs HTML text that keeps displaying in the browser window the multiples
of the integer 2, namely 2, 4, 8, 16, 32, 64, etc. Your loop should not terminate (you should
create an infinite loop). What happens when you run this program?
14.27 A company wants to transmit data over the telephone, but they are concerned that their
phones may be tapped. All of their data is transmitted as four-digit integers. They have asked you to
write a program that will encrypt their data so that it may be transmitted more securely. Your script
should read a four-digit integer entered by the user in a prompt dialog and encrypt it as follows: Replace
each digit by (the sum of that digit plus 7) modulus 10. Then swap the first digit with the third,
and swap the second digit with the fourth. Then output HTML text that displays the encrypted integer.
Write a separate program that inputs an encrypted four-digit integer and decrypts it to form the original
number.
e-Business and e-Commerce: How to Program, by Harvey M. Deitel, Paul J. Deitel, and Tem R. Nieto. Published by Prentice Hall.
Copyright © 2001 by Pearson Education, Inc.