Show Bid Request
Interpreter
Bid Request Id: 28707
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Posted by: |
rm54 (3 ratings)
(Software buyer rating 9.66 )
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Non-action Ratio: |
Below Average - 58.82%
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Posted: |
Sep 25, 2002
7:04:42 PM EDT
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Bidding Closes: |
Sep 28, 2002
8:00:00 PM EDT
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Viewed (by coders): |
277 times
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Deadline: |
10/1/2002 8:00:00 AM
TIME EXPIRED
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Description:
Write Java classes to support a processing of arithmetic expressions in prefix notation called PNInterpreter.
Expressions in prefix notation contain an operator first and then the operands on which the operation is performed. For
example, + 3 4 is equal to 3 + 4 in the infix notation. For this assignment your program should support integers only
and the following operators: + - * / ^.
There are a variety of ways to implement the prefix notation interpreter. One way is to use stacks. Another would be to
use a tree. Chose either one of the two ways and implement the necessary data structures instead of using the built-in
Java classes. Trees and stacks and their implementation are discussed in most data structure textbooks.
Your interpreter should accept strings of operators and operands seperated by spaces (no parenthesis) and return each
operation it performed and the final result or output an error if the input is invalid.
Write a main program that calls the test on your implementation to demonstrate that it works correctly.
Call the main class PNInterpreterDriver. Write a test method testInterpreter that works with an object of
your implementation of PNInterpreter. testInterpreter should be able to read from standard input a list of
expressions like this:
* + 2 * 4 6 + 3 5
- - / 3 4 * 5 6 2
- 3 2 + 2
quit
”quit” (or encountering the end of stream) is the signal to stop reading from the standard input. The test method (using
StreamTokenizer or similar built-in stream class) should read these commands and act appropriately. For example, with
the following test file, you might see something like this as the output of the program:
brillig(65)#java PNInterpreterDriver < test1.txt
Testing string: * + 2 * 4 5 + 3 5
operation performed: 4 * 6, result 24
operation performed: 2 + 24, result 26
operation performed: 3 + 5, result 8
operation performed: 26 * 8, result 208
Final result: 208.
Testing string: - - / 3 4 * 5 6 2
operation performed: 3 / 4, result 0
operation performed: 5 * 6, result 30
operation performed: 0 - 30, result -30
operation performed: -30 - 2, result -32
Final result: -32.
Testing string: - 3 2 + 2
operation performed: 3 - 2, result 1
invalid expression, reached end of expression
command: quit
Testing complete.
Deliverables:
1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done.
2) The program MUST meet the specifications EXACTLY. In other words, DO NOT add any extra "features". If it doesn't ask for a GUI or extra mathematical features, don't include it!
3) Complete ownership and distribution copyrights to all work purchased.
Platform:
This program is to be written in Java only so it should be platform independent.
Must be 100% finished and received by buyer on:
Oct 1, 2002 8:00:00 AM EDT
Deadline legal notes: All times are expressed in the time zone of the site EDT (UT - 5). If the buyer omitted a time, then the deadline is 11:59:59 PM EDT on the indicated date.
Special Conditions / Other:
This project MUST be completed by Tuesday, October 1, 2002, 8:00am EST, US. Do not bid on this project if you cannot meet the deadline.
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Bidding/Comments:
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Bid Amount
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Coder Rating |
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This bid was accepted by the buyer!
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$10 (USD)
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Sep 25, 2002
9:46:00 PM EDT
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9.4
(Superb)
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Hi,
I have already written this program. If you accept my bid, I will modify it to your needs. This is a very nice and simple project, and so wouldn't require more than 2 hours to complete for you.
If you have any questions, please ask!
Best Regards,
elohmrow
aka Bradley Andersen |
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