Assignment 1 | TA Ranking System in COBOL and C Solution

    • Introduction


Teachers always want to nd the best and dedicated TAs for their courses. Di erent courses require di erent skills sets. Di erent TAs have di erent skills and also preferences for the courses that they are interested in. In this assignment, you have to implement part of a TA matching system. Your program should help each course to rank the top 3 TAs. You are required to implement it once using COBOL and once using C.


    • Assignment Details


Jimmy is designing a simple TA Matching System (the \System" hereafter) to nd the most suitable TAs for each course. He is asking you to implement the TA ranking module of this system. The system reads 1) the courses’ requirements as well as 2) the candidate TAs’ skills and preferences as input, and reports the top 3 TAs for each course, where TAs are ranked by matching scores (to be explained later).


2.1    TA ranking system

In this System, course instructors will enter their requirements for TAs: 3 required skills, and 5 optional skills. Candidate TAs will enter their pro les: 8 skills, and their 1st, 2nd and 3rd preferred courses.

The System keeps the course instructors’ requirements in a le: instructors.txt. Each line of the le represents the requirements of a course, containing the course ID, required skills, and optional skills. Also, the System keeps another le containing all the candidate TAs’ information: candidates.txt. Each line of the le records a candidate TA’s information, including the TA ID, skills, and preferred courses. Figures 1 and 2 give an example of the instructors.txt and candidates.txt les (spaces are explicitly displayed as ) respectively. Notice that skill names are padded by spaces so that each skill name takes exactly 15 characters. Some skill names may contain multiple words and have spaces between words, e.g. Shell script .


Jimmy has designed the following policy regarding the matching score that measures how suitable a candidate is to be the TA of a course. The matching score of each pair of (course, TA) is computed as:


score(course; T A) = (
1
+ skill score + preference score
if all the required skills are satis ed

0

otherwise









1






Course ID    Required skills    Optional skills









Figure 1: Sample of instructors.txt





2




TA ID    Skills    1st    2nd    3rd











Figure 2: Sample of candidates.txt
where


skill score: number of optional skills satis ed by the TA

preference score: TA’s preference to the course, according to the following table





1st preference
2nd preference
3rd preference






preference

score
1.5
1
0.5








Taking the instructors.txt and candidates.txt in Figures 1 and 2 respectively as an example:



score(3180; 1155136773) = 1 + 5 + 1:5 = 7:5

score(3180; 1152147332) = 0


The output.txt le should not output the matching scores of every TA for each course directly, but reports only the top 3 TAs for each course. Figure 3 is an example of the output.txt le. Note that, if less than k candidates satisfy the required skills speci ed by the course, the Rank-k TA for that course is lled with 0000000000 :


Besides, pay attention to the cases that the instructors.txt le or the candidates.txt le is empty. If the instructors.txt le is empty, the output.txt le should be empty too; if the candidates.txt le is empty, the Rank-k TA for all the courses should be lled with 0000000000 .


Course ID    Rank-1 TA    Rank-2 TA    Rank-3 TA








Figure 3: Sample of output.txt

Jimmy needs your help. You are required to implement a program to generate the ranking report of each course.


2.2    General Speci cation

You are required to write two programs, one in COBOL and the other one in C, for the student ranking module of the System. You should name your COBOL source as \ta ranking.cob" and your C source as \ta ranking.c".



    1. Input and Output Speci cation

Your programs should read two input les: instructors.txt and candidates.txt, which contain instructors’ requirements and candidates’ skills and preferences. The detailed spec-i cation of input format is given in Section 2.3. For each course, your program needs to calculate the matching score for each candidate. These calculations should be strictly based on the policy described above. Afterwards, TAs are ranked by their matching scores with each course. In case of a tie (two TAs having the same matching score), the TA with lower TA ID will have a better rank than the other. Your program should output one le to report

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the top 3 TAs for each course and display them in ranking order (i.e. the rst one is the best TA, the second one is the second best and so on). The output le format should follow the description in Section 2.4. You can \hardcode" the input le names in your program. And the naming of the output le should be: output.txt.

    2. Restrictions on using COBOL and C

For COBOL, in order to force you to program as in the old days, ONLY 2 keywords are allowed in selection and loop statements: \IF" and \GOTO". You are not allowed to use modern control constructs, such as if-then-else or while loop. Using any other keywords will receive marks deduction. But for C, you can use whatever you want.

    3. Error Handling

The programs should also handle possible errors gracefully by printing meaningful error messages to the standard output. For example, your program should be able to check whether the input le exists or not. If not, display a warning message "non-existing le!". However, you CAN assume that the input les are free of format on content errors.

    4. Good Programming Style

A good programming style not only improves your grade but also helps you a lot in debugging. Poor programming style will receive marks deduction. Construct your program with good readability and modularity. Provide su cient documentation by commenting your codes properly but never redundantly. Divide up your programs into subroutines instead of clogging the main program. The main section of your program should only handle the basic le manipulation such as le opening and closing, and subprogram calling. The main purpose of programming is not just to make the program right but also make it good.

    5. Other Notes

You are NOT allowed to implement your program in another language (e.g. Java/Python) and then initiate system calls or external library calls in COBOL and C. Your source codes will be compiled and PERUSED, and the object code tested!

Do not implement your programs in multiple source les. Although COBOL and C do allow you to build a project with subroutines scattered among multiple source les, you should only submit one source le for each language.

NO PLAGIARISM!!!! You are free to design your own algorithm and code your own implementation, but you should not \borrow" codes from your classmates. If you use an algorithm or code snippet that is publicly available or use codes from your classmates or friends, be sure to DECLARE it in the comments of your program. Failure to comply will be considered as plagiarism.

A crash introduction to COBOL will be given in the upcoming tutorials. Please DO attend the tutorials to get a brief idea on COBOL, and then learn the language by yourselves. We assume that you are pro cient in C. For a more in-depth study, we encourage students to search relevant resources on the Internet (just Google it!).


2.3    Input File Format Speci cation

There are two input les: instructors.txt, and candidates.txt. All input les are in plain ASCII text. Each line is ended with the characters \nrnn" on windows machine, including the last line. You can write your programs on whatever OS you like, but please verify that they can be compiled and run correctly on Windows machines in SHB924/909 because we will grade your assignment there. You should strictly follow the format as stated in the following.


Each line of instructors.txt contains nine elds of xed length for a course. The lines are sorted by course IDs in ascending order.

        1. Course ID: a 4-digit number followed by a space.


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        2. Required skills: 3 required skills, each of which is a string of 15 characters (spaces are padded at the end in case the skill name is less than 15 characters).

        3. Optional skills: 5 optional skills, each of which is a string of 15 characters (spaces are padded at the end in case the skill name is less than 15 characters).

Each line of candidates.txt contains twelve elds of xed lengths of a candidate’s skills and preferences. The lines are sorted by TA IDs in ascending order.

        1. TA ID: a 10-digit number followed by a space.

        2. Skills: 8 skills, each of which is a string of 15 characters (spaces are padded in case the skill name is less than 15 characters).

        3. Preference: 3 preferences, each of which is a 4-digit number followed by a space.

You may make the following assumptions on the    les:

{ All input les strictly follow the format speci ed in Section 2.3. { File instructors.txt is sorted by course ID in ascending order. { File candidates.txt is sorted by TA ID in ascending order.

{ The number of skills in le candidates.txt is xed to 8, and there are no duplicate skills.



2.4    Output File Format Speci cation

There is only one output le: output.txt. You should strictly follow the format as stated in the following.


Each line of output.txt contains 4 elds of xed lengths of the top 3 TAs for each course. The lines should be sorted by course IDs in ascending order (the same order as in \instructors.txt\).

        1. Course ID: a 4-digit number followed by a space.

        2. Rank-1 TA: The best TA, which is a 10-digit number followed by a space. If no candi-dates satisfy the required skills speci ed by the course, this eld is lled by 0000000000 .

        3. Rank-2 TA: The 2nd best TA, which is a 10-digit number followed by a space. If less than 2 candidates satisfy the required skills speci ed by the course, this eld is lled by 000000000 .

        4. Rank-3 TA: The 3rd best TA, which is a 10-digit number followed by a space. If less than 3 candidates satisfy the required skills speci ed by the course, this eld is lled by 0000000000 .


Pay attention to the special cases, as we have mentioned in the previous sections:

{ For Rank-k TA of a course, if less than k candidates satisfy the required skills speci ed by the course, the Rank-k TA for that course is lled with 0000000000 .

{ If the instructors.txt  le is empty, the output.txt  le should be empty too.

{ If the candidates.txt le is empty, the Rank-k TA for all the courses should be lled with 0000000000 .

{ If the input  le is non-existent, display a warning message "non-existing  le!".









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2.5    Report

You should give a simple report to answer the following questions within one A4 page:


    1. Compare the conveniences and di culties in implementing the TA Ranking System in COBOL and C. You can divide the implementation into speci c tasks such as \reading le in certain format", \simulating loops", \procedure/function call" and so on. Give code segments in your programs to support your explanation.

    2. Compare COBOL with modern programming languages (e.g. Java/Python/...) from di erent aspects (e.g. variable declarations, paradigm, data type, parameter parsing, ...). You are free to pick your favorite modern programming language.

    3. Do you think COBOL is suitable for writing applications like in this assignment, especially when some of the input needs to be passed several times? Explain in terms of, say, the aspect like programming di culty, e ciency of you program, etc.

    4. In your program design, how do you separate the tasks into submodules? Tell us brie y the functionality of each submodule and the main ow of your program in terms of these submodules.


    • Submission Guidelines


Please read the guidelines CAREFULLY. If you fail to meet the deadline because of submission problem on your side, marks will still be deducted.

The late submission policy is as follows:

    • 1 day late: -20 marks

    • 2 days late: -40 marks

    • 3 days late: -100 marks

So please start your work early!


1. In the following, SUPPOSE

your name is Chan Tai Man,

your student ID is 1155234567,

your username is tmchan, and

your email address is tmchan@cse.cuhk.edu.hk.

    2. In your source les, insert the following header. REMEMBER to insert the header according to the comment rule of COBOL and C.

/

CSCI3180 Principles of Programming Languages


--- Declaration ---
I declare that the assignment here submitted is original except for source material explicitly acknowledged. I also acknowledge that I am aware of University policy and regulations on honesty in academic work, and of the

disciplinary guidelines and procedures applicable to breaches of such policy
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and regulations, as contained in the website

http://www.cuhk.edu.hk/policy/academichonesty/


Assignment 1

Name : Chan Tai Man

Student ID : 1155234567

Email Addr : tmchan@cse.cuhk.edu.hk
/

The sample    le header is available at

http://course.cse.cuhk.edu.hk/~csci3180/resource/header.txt

    3. Make sure you compile and run the COBOL program without any problem with OpenCOBOL 1.1.0 and gcc 2.95.2 on Windows computers in SHB924/904. We will grade your works based on those machines.

    4. The report should be submitted to VeriGuide, which will generate a submission receipt. The report and receipt should be submitted together with your COBOL and C codes in the same ZIP archive.

    5. The COBOL source should have the lename \ta ranking.cob".The C source should have the lename \ta ranking.c". The report should have the lename \report.pdf". The VeriGuide receipt of report should have the lename \receipt.pdf". All le naming should be followed strictly and without the quotes.

    6. Tar your source  les to username.tar by


tar cvf tmchan.tar ta ranking.cob ta ranking.c report.pdf receipt.pdf


    7. Gzip the tarred le to username.tar.gz by gzip tmchan.tar

    8. Uuencode the gzipped le and send it to the course account with the email title \HW1 studentID yourName" by

uuencode tmchan.tar.gz tmchan.tar.gz n

j mailx -s "HW1 1155234567 Chan Tai Man" csci3180@cse.cuhk.edu.hk

    9. Please submit your assignment using your Unix accounts.

    10. An acknowledgement email will be sent to you if your assignment is received. DO NOT delete or modify the acknowledgement email. You should contact your TAs for help if you do not receive the acknowledgement email within 5 minutes after your submission. DO NOT re-submit just because you do not receive the acknowledgement email.

    11. You can check your submission status at http://course.cse.cuhk.edu.hk/~csci3180/submit/hw1.html.

    12. You can re-submit your assignment, but we will only grade the latest submission.

    13. Enjoy your work :>
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