CS125: Introduction to Programming Principles

CS125 Spring 2008
Assignment 1
Due: Monday, May 26th, 11:59pm

Note: Download A01.zip before beginning to code your solutions.

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Question 1: Dice (25%)

Write a program called Picture.java which generates the following picture;

Files to Submit: Picture.java

Question 2: Traffic Lights (25%)

Write a program called Traffic.java that will create a 1-D board with eight squares in it, and allow the user to click on the board 6 times.

On the first three clicks a green traffic light is placed on the square that the user clicked on.

As well, each time the user clicks on the board if there was a green light already on the board it turns yellow, if there was a yellow light on the board it turns red, and if there was a red light on the board it is removed.

For instance if the user clicks on the leftmost square the board would be:

Then if the user clicks on the rightmost square, the first light turns from green to yellow, and a green light is placed on the rightmost square:

Note the following:

• The last three clicks do not place a new light on the board, but merely advance the existing traffic lights ahead one step.
• The board should be empty after the sixth mouse click.
• Assume the three green traffic lights are all placed on different squares.
• Working through this question step by step for each mouse click will help you better understand what is happening.

Files to submit: Traffic.java

Question 3: Email Generator (25%)

Write a program called EmailMaker.java which reads in a person's name and outputs an email address for that user.

When the program is run, the user will type in their first name, middle name, and last name. The email adress is generated as follows:

• The first letter of their first name (in lower case)
• Followed by the last letter of their middle name(in lower case)
• Followed by all but the first and last letters of their last name (in upper case)
• "@cs.uwaterloo.ca" is appended to the end.

For instance, if the user types in their name as: "Harry James Potter" their email address would be:

Note the following:

• The only output your program should produce is the email address generated, Do NOT output any user prompts for the parts of the name. (i.e. DO NOT ask "enter your name")
• Assume the name entered always has three parts to it, and the last part has at least three characters in it.
• Each part of the name will be separated by at least one space when entered.
• Your program should work regardless of how the user capitalizes their name. For instance, if the user had typed in "HARRY JAMES POTTER" the email address produced should be the same.

Files to submit: EmailMaker.java

Question 4: CAS Numbers (25%)

Write a program called CASGenerator.java which will read in a chemical number and output the equivilent CAS(Chemical Abstracts Service) number. A CAS number is a standard way Chemists can identify the many chemicals they need to work with.

Many numbers used to track people and information contain a built in error-checking mechanism. When the number is first generated, the digits of the number are combined in some mathematical fashion to produce an extra "check digit" which is added to the end of the original number. Programs can identify that a number entered is invalid by checking to see if the last digit entered matches what the calculation should produce.

For this exercise you will be performing the CAS check digit calculation. Your program will input a chemical number as an integer from 1000 to 9999 (ie. 4 digits long), calculate the CAS check digit, and then output the new five digit CAS number.

The CAS check digit calculation is as follows. Read carefully. Take the least significant digit of the chemical number and multiply it by 1. Add to that number, the next digit multiplied by 2. Then add to that the next digit multiplied by 3, and so on until all the digits of the chemical number have been used. The check digit is the remainder of the final number that was added up, when divided by 10. (i.e. The addition modulo 10.)

For instance, D-glucose has been assigned a chemical number of 5099. The check digit for this number is found by; (9x1) + (9x2) + (0x3) + (5x4) = 47. Then the remainder of 47 when divided by 10 is the check digit. (i.e. 47 Modulo 10). Thus, the CAS number produced would be 50997.

Note the following:

• Your program must read in an integer (Not a string). The provided java program already does this for you. You may not convert that number to a String to extract the digits, you MUST get them mathematically.
• The provided code prompts the user for a chemical number. The only other output your program should produce is the final CAS number.
• You may assume the user inputs a valid number between 1000 and 9999.

Files to submit: CASGenerator.java

Program Style and Documentation

Marks will be awarded on this and all future assignments for appropriate documentation and program style. The markers will, in particular, be looking at the following:

• A program header at the top of each file, which includes your name, userid, student id number, and lab section.
• Appropriate and meaningful variable names, following conventions discussed in class.
• Comments on blocks of code, briefly explaining the purpose of those lines of code.
• Appropriate use of white space (including blank lines and indentation), so that code looks well-organized and is easy to read.

Submitting your Assignment

You will need to submit your assignment electronically just as you did for Assignment 99. Click here to go to the Assignment 1 submission page.

Please submit your solution to each question as you complete it. If you modify your solution later, you can simply submit the new code. It will replace the previous submission. You are strongly advised to attempt to submit the files early, to ensure that you do it successfully. Be sure to follow the instructions to check that your files were submitted.

Required Files:

• Picture.java
• Traffic.java
• EmailMaker.java
• CASGenerator.java