Shopping
Lab 1 (CS1101 AY2008/9 Semester 1)
This lab assignment is graded.
Date of release: 2 September 2008, Tuesday, 23:59.
Submission deadline: 10 September 2008, Wednesday, 23:59.
School of Computing, National University of Singapore

0 Introduction

This is your first graded lab. You have one week to complete this lab.

This lab requires you to do two exercises. You are advised to review the material covered in chapters 1 through 4 and read Programming Style, Design and Marking Guidelines before attempting this lab assignment. You should not use syntax or constructs not covered in lectures; you shouldn't need to and may even be penalized for doing so (if the objective of the assignment is undermined). Unless a template is given, you should start each program afresh (ie. don't cut and paste and modify) so that you get sufficient practice with writing a complete Java program.

A word of advice: Code incrementally. Don't try to finish all parts of a program then compile it. Write your program in bits and pieces and compile frequently. Try to maintain a compilable program even while you are working on it. Submitting a compilable program that partially works is better than submitting an un-compilable one. This last point especially applies to the programming exams. Seriously, code incrementally.

The following topic has not been covered and hence you should not use them:

• Arrays and any of the Java Collection classes.

Note that:

• You may assume that all input data are correct. Hence you do not need to do input data validation.
  
  
• You should use Scanner class on System.in for input and System.out for output in your programs, unless otherwise stated.
  
  
• You should use println() instead of print() for the last line of output your program generates.
  
  
• You should not use multiple instances of Scanner class, that is, you should not have more than one variable of this class.
  
  
• Test your programs thoroughly with your own input data before you submit to CourseMarker. Do NOT use CourseMarker as a debugging tool.
  
  
• You do not need to worry too much about your marks for "Features" and "Typography" tools in CourseMarker. Pay attention to "Dynamic Tests", as this is the result of CourseMarker testing your program with unknown test data. We will not release the test data.
  
  
• Even if you get full marks for "Dynamic Tests" from CourseMarker, it might not mean that your program is correct. Your leader will test your program with more data if necessary, and he or she can overwrite CourseMarker's marks.
  
  
• The marks you get from CourseMarker is for your reference only. Your discussion leader will go through your programs and give marks accordingly.
  
  
• Do not submit your program in the last minute.

For more information on CourseMarker, please refer to CS1101X lab page.

For this lab, the number of submissions is set to 15. For subsequent labs, it may be reduced. Only your last submission will be graded.

If you have any questions, you may post your queries in the IVLE forum of your respective lecture group. Do not post your programs (partial or complete) in the forum before the deadline!

1 Exercise 1: Lat-Long Verifier (40%)

1.1 Learning objectives

• Standard input and output. (Textbook sections 3.7, 3.23)
• The double data type. (Textbook sections 3.10, 3.13)
• if Statements. (Textbook sections 4.3)
• Simple arithmetic comparison on double. (Textbook section 4.6)

1.2 Task

Write a program that checks that a pair of latitude and longitude coordinate point is in Singapore.

You may assume that we use a bounding-box to represent Singapore. A coordinate point is in Singapore if it falls within the range where (1.2427 < lat < 1.4548) AND (103.6271 < long < 103.9993).

1.3 Sample run

Sample run using interactive input (user's input shown in blue; output shown in bold purple):

$ javac LatLong.java
$ java LatLong
Enter Latitude: 1.3126
Enter Longitude: 103.8634
(1.3126, 103.8634) is in Singapore.

Another sample run is shown below

$ javac LatLong.java
$ java LatLong
Enter Latitude: 1.1168
Enter Longitude: 103.6272
(1.1168, 103.6272) is not in Singapore.

1.4 Submission

Submit your program through CourseMarker.

1.5 Important notes

• When assigning variable names, be careful to note that some identifier names are reserved by Java.
  
  
• A skeleton file is provided here: LatLong.java

2 Exercise 2: Simple Shopping Cart (60%)

2.1 Learning objectives

• Standard input and output. (Textbook sections 3.7, 3.23)
• The int data type. (Textbook sections 3.10, 3.13)
• Simple arithmetic operations on int. (Textbook section 3.15)
• String Concatenation (Textbook section 3.22)
• if Statements. (Textbook sections 4.3)
• String comparisons (Textbook section 4.5)

2.2 Task

In this exercise, you are to write a simple shopping cart program. Your task is to write a program that accepts up to three sets of input.

Each set of input is an item with item name, cost (in cents) and quantity. After entering the details for each set, the user is prompted if he wants to insert more items (up to two times).

After three items have been entered or when the user has selected not to add more items, the program will print out the total cost in dollars and cents as shown in the sample runs below.

Note that you are not allowed to use arrays in this exercise.

Some lecture groups will only cover repetition structures (loops) this Friday, so you need not use loop for Exercise 2. The exercise is set in such a way that it can be written without using loop (although the code will be slightly longer than one that uses it). However, if you choose to use loop, it is fine too.

While this may seem to be a tough lab, if you work it out step by step and test each part of your code incrementally, you will not have any problems. However if you try to code finish the entire lab without compiling at all, you will definitely have problems.

Hint: Try to first code the data input and output for the FIRST item. After you have done that, check to see that the input and output corresponds to the sample run. If you are successful, code the data entry for the second item and then the third item.

2.3 Sample run

Sample run using interactive input (user's input shown in blue; output shown in bold purple):

$ javac SimpleCart.java
$ java SimpleCart
Enter item name: Blue Pen
Enter cost for each item: 40 
Enter quantity: 4 
Do you wish to add more items? (y/n): y
Enter item name: Ruler
Enter cost for each item: 100 
Enter quantity: 1 
Do you wish to add more items? (y/n): y
Enter item name: Eraser
Enter cost for each item: 40 
Enter quantity: 2
Total: $3.40

Another sample run is shown below:

$ javac SimpleCart.java
$ java SimpleCart
Enter item name: Blue Pen
Enter cost for each item: 40 
Enter quantity: 4 
Do you wish to add more items? (y/n): n 
Total: $1.60

2.4 Submission

Submit your program through CourseMarker.

2.5 Important notes

• Note that your output must adhere strictly to the given format as shown in purple in the example. Any output that contains mis-spelling, additional character, omission of character, etc. will be graded as incorrect by CourseMarker. Note that the text that you prompt the user for input is also considered as part of the output.
  
  
• A skeleton file is provided here: SimpleCart.java

2.6 For discussion

• You can see that you have repeated our code multiple times to gather user input. In the real world, a user may purchase 20 to 30 different items. Using what you have learnt this week, how can you rewrite your code so that the user may enter an arbitrary number of items without the multiple repetitions?

3 Deadline

The deadline for handing in all programs is 10 September 2008, Wednesday, 23:59. Late submissions will NOT be accepted.

• 0 Introduction
  
  
• 1 Exercise 1: Lat-Long Verifier (40%)
  • 1.1 Learning objectives
  • 1.2 Task
  • 1.3 Sample run
  • 1.4 Submission
  • 1.5 Important notes
  
  
• 2 Exercise 2: Simple Shopping Cart (60%)
  • 2.1 Learning objectives
  • 2.2 Task
  • 2.3 Sample run
  • 2.4 Submission
  • 2.5 Important notes
  • 2.6 For discussion
• 3 Deadline