” COMP2100作业 写作、 辅导programming作业、C++程序Copyright 2020 Macquarie University.Data File Lab Assignment 1COMP2100 Revised 6 August 2020This lab is the first of two assignments in COMP2100.Commences: Week 1.Progress: 4pm, Tuesdays of weeks 4, 5, 7, break: 18 Aug, 25 Aug, 8 Sep, 15 SepDue: 4pm, second Tuesday of the break 22 September 2020Value: 25% (16% for task, 4% weekly progress, 5% for code explanation)1. IntroductionThis is the first of two programming task assignments in COMP2100. In this assignment, you willwork with binary data stored in files, using the Unix I/O interface to read and write such files.The first part of this document Describes the assignment (Data File Lab) in detail. Individual sectionsdiscuss an overview of the lab, how to fetch your personalised assignment specification, how yousubmit your work and obtain automatic feedback while you are working, and how the markingscheme works.The second part of this document describes each stage of the lab assignment. You should read thispart to understand your task in each lab stage, and you should also refer to the personalisedassignment specification for each stage. You obtain your personalised specification using the labcommand. You should ensure that your personalised specification is kept secure at all times.You should also read the relevant support documents on iLearn in the section Programming TaskSupport Notes. The Lab Command Manual will enable you to perform key tasks including checkingyour marks and applying for free extensions it is relevant to both assignments in this unit. Thereare documents that define what we expect in programming style, and support notes on Cprogramming including some key ideas that are relevant to this Data File Lab.This document is Copyright 2020 by Macquarie University. Neither this document nor any part ofthe assignment may be communicated to any unauthorised person or through any unauthorisedservice or website.2. Overview of the LabData files exist in various formats. In Unix, text files are common for simple data, but large data filesare stored as binary data. In this lab assignment (programming task), you will be developingprograms to read, write, modify, and reformat the data in binary data files. The assignment consistsCOMP2100作业 写作、 辅导programming作业、C++程序语言作业调试、c/c++实验作业 写作of a sequence of stages which build on each other. The first three stages develop your skills. In thefinal stage you will reverse engineer a data file using your knowledge of data representations. Youhave the choice between an easier final stage (stage 4) that can earn you at most 3 marks for thestage, or a more difficult final stage (stage 5) worth up to 4 marks for the stage. You may attemptboth stages 4 and 5, but only the maximum of the two marks will count towards your total.Copyright 2020 Macquarie University.The marking outline is:Section ValueStage 1 3Stage 2 3Stage 3 3Stage 4 (max 3 marks) orstage 5 (max 4 marks)4Code style 3Progress 4Code comprehension 5Total 25Learning OutcomesThis assignment will involve you in developing the following specific skills and capabilities. Able to write programs that use C data structures, pointers and arrays. Able to read and write binary data files, and write data in text format. Able to convert between different data representations. Able to use malloc and free to construct data structures using the heap. Able to implement simple command line parameters. Able to interpret and recognise binary data representations. Research Unix library and system calls3. Fetching your lab assignmentThe lab assignment files are accessed through the lab command which can be found at/home/unit/group/comp2100/labThere is no Unix man page for the lab command (it is not a Unix system command) but there isdocumentation on iLearn and if you dont give it any command-line parameters or options then itwill print out some Brief documentation itself (a similar feature is common in many Unix programs).To see how this works, try the following command (where the $ symbol represents the Unixcommand-line prompt you should type the command that is underlined in this example).$ /home/unit/group/comp2100/labThe option g is used to get a lab stage. For example, to get lab 1 stage 1, do:$ /home/unit/group/comp2100/lab g 1.1For stage 2, the option would be g 1.2 instead. Please see the Lab Command Manual in iLearnfor more information about the lab command, including options for submitting assignments, gettingmarking reports, checking due dates and claiming your free extension days. Also, you can set upyour Unix account so that you can abbreviate the command and just type lab instead of the fullpath name /home/unit/group/comp2100/lab. For the rest of this document, we will usethe abbreviated name.The lab get command downloads your lab data as a tar file. For stage 1, the tar file is stage1.tar.Copyright 2020 Macquarie University.Tar is an archive utility (like zip) it stores many files packed into one file. Use tar to extract thecontents of this file. You can read all about tar in the Unix man page$ man 1 tarHere is the command to extract the contents of stage1.tar.$ tar xvf stage1.tarThis will create a directory called stage1 and put the downloaded files in that directory.4. Feedback during the assignment, submission and markingIn this assignment, you can submit your code as often as you like, and receive immediate feedbackand marks. There are rewards (progress marks) for working consistently throughout the assignmentperiod and achieving stages of work by their due dates. Most of your final mark will be computedfrom the results of the automarker. A small number of marks are awarded for code style which ismanually marked after the assignment closes.The maximum mark for the assignment is 20 marks. Of those marks, 13 marks are for achievementsin the various stages, 4 marks are for progress and 3 marks are for code style.A. Introduction to COMP2100 automarkingThis is the first of two lab assignments in COMP2100. In both assignments, an automarker will trackyour progress and provide feedback to you. This is more than just telling you your mark it is afeedback mechanism designed to help you as you work through the assignment. Firstly, thefeedback is immediate, so when you think you have solved a problem you can submit your revisedsolution and see immediately whether it has enabled you to pass the automarker tests. Secondly,the automarker provides a detailed breakdown of your mark, which can help you isolate specificproblems (such as a memory leak when using malloc and free). Thirdly, the automarker sometimesprovides specific hints to help you understand what you need to address such as identifying whichcolumns of your data file are incorrect.You cannot rely only on the automarker, however. In this assignment, you will be provided with testdata files, and you can and should compile your program yourself and run it on the test data files,examining the output yourself and identifying errors in your code. The automarker does not replacegood old-fashioned debugging one of the essential skills for all programmers.B. Individual work And information resourcesThe stages of the lab are based on data files that will be provided to you. Each student will havetheir own specific data files to work with, with their own unique data format.This lab must be your own work. However, you may use resources on the Internet to obtain generalinformation including information about the C language and libraries, information about binary andtext data formats, and information about the operating system. If you obtain useful informationfrom the Internet, you must include comments at the relevant points in your code acknowledgingthe source of the information (URL) and briefly describing the key idea(s) that you are using.(Exception: information from the Unix manual pages does not require citation in your program).The Unix manual pages are available online on ash and iceberg use the man command. You canalso find Unix manual pages online through Google. For example, to find out about the printflibrary call, use the command man 3 printf or Google man printf and to find out about thedirectory listing command ls, use the command man ls or Google man ls. However, youCopyright 2020 Macquarie University.should be cautious about using information found online because sometimes there are differencesbetween different Unix systems and our systems may not behave exactly the same as described insome online documentation.The manual pages on the system (man command) are divided into sections:1. System commands such as ls, wc, etc.2. Unix system calls such as read(), open(), etc.3. Unix library such as printf(), fopen(), etc.4. Sections 4-8 contain other information.For more information on the man command, use the command man man to read the manualpages about the man command.C. Submitting your lab solution achievement marks [13 marks]Your lab solution can be submitted using the lab command. The option s is used to submit asolution to a lab stage. After the option, list all the files that you want to submit. Each time yousubmit, it is treated as a fresh submission, so you must list all the files that you want to submit everytime. (If you find that tedious, learn about wildcards in the bash shell.) For example:$ lab s 1.1 stage1.c sub.c defs.hThe lab utility sends your submitted files to a server which compiles the C files together into aprogram, runs it, and tests that it works correctly for your particular lab assignment. The serverrecords information about your submission and also sends back information to you through the labcommand.You can submit as many times as you like. As a matter of personal achievement, you should aim toachieve a really good score on your initial submit, having checked that your program compileswithout errors and performs correctly on the provided sample data files. However, if there areproblems identified by the auto marker, you can resubmit without penalty.You must download each stage before you attempt to submit a solution to that stage. Further, youneed to download each stage because the download provides you with the input and output datafiles that you need in order to test your program yourself.The marks awarded by the automarker for each stage of the assignment are called the achievementmarks for that stage.D. Progress marks [4 marks]Each lab assignment includes marks that are awarded for progress on the task at specified dates(approximately each week). The lab assignments are to be done both during lab sessions (with theassistance of lab supervisors) and in your own time. Each week that the lab is out, you earn aprogress mark if you achieve the specified milestone by 4 pm on the specified date. Each milestoneis achieving a mark of at least 2.0/3.0 in a specific assignment stage. You can earn the progressmarks early, but you cannot earn them late.If you do not achieve the milestone for a progress mark by the specified date then you lose thatweeks progress mark and the milestone slips and becomes due on the next progress date. All thelater milestones also slip to the next due date, but the last milestone is lost. If you achieve theslipped milestone By the new progress date then you receive the progress mark for that date, butyou have lost the progress mark for the missed date and you cannot make it up later.Copyright 2020 Macquarie University.In the lab command, progress marks are identified by the date that they are due.The Milestones Tuesday of Week 4: Stage 1 achievement mark of at least 2.0/3.0 Tuesday of Week 5: Stage 2 achievement mark of at least 2.0/3.0 Tuesday of Week 7: Stage 3 achievement mark of at least 2.0/3.0 Tuesday of the first week of the break: Stage 4 or 5 achievement mark of at least 2.0/3.0 or2.0/4.0 Tuesday of the second week of the break: Lab closesExampleSarah earns 2.0/3.0 for stage 1 of the assignment on the Monday of week 4 (17 August). Shereceives the first progress mark. Her work on stage 2 is delayed, and she has not achieved 2.0/3.0for stage 2 of the assignment when the second progress milestone falls due, so she misses thatprogress mark. She achieved 2.0/3.0 in stage 2 later that same week and is awarded the thirdprogress mark because that is the next progress milestone date. When she achieves 2.0/3.0 in stage3 later on, she is awarded the final progress mark. She cannot be awarded a progress mark forachieving 2.0/3.0 in stage 4 because she missed the earlier progress mark.E. Code Style [3 marks]We will mark one of your submitted programs for code style. We recommend that you adhere tocode style guidelines for all your programs. See the documents Some Important Comments on CodeStyle and Systems Programming Style.Each time you submit a lab 1 solution using the lab command, you will be notified which version ofyour program will be marked for style. The decision is made by an algorithm (see below). We preferto mark later stages of the lab where your programs will be more sophisticated. However, we prefernot to mark programs where you have not yet solved the stage.The stage selected for style marking is the latest stage for which you achieved a mark of atleast 2.0. For example, if you earn 3.0 marks in stage 1, 2.8 marks in stage 2, 2.1 marks instage 3 and 1.9 marks in stage 4, we will mark your stage 3 submission for style. We willmark the last successful or forced submission to that stage. Whenever you submit, thelab command clearly tells you what stage will be marked for style, and whether it is theprogram that you just submitted that will be marked for style.All your programs should be written with good style. If you write with consistently good style thenyou wont be caught out with a poor style mark if (for example) you manage to achieve 2.0 marks instage 4 at the last minute and have no time left to improve the style of your program!F. Code Explanation [5 marks]During the semester, your tutor will provide an opportunity for you to demonstrate that you canexplain the code you have written. You will show the tutor your program for a particular stage, andanswer some questions about it. Your mark for this task will be recorded in iLearn as 0, 1 or 2 out of2, but will be scaled to be worth 5% of your final grade. You will receive full marks (2 out of 2) forclearly Demonstrating that you can explain how your code works and why you wrote it as you did.You will receive half marks (1 out of 2) if your explanations demonstrate only a limitedunderstanding of your code. You will receive a mark of zero if you are unable to explain your code.Copyright 2020 Macquarie University.5. Detailed information about markingThe lab command computes your marks and records them on the server. Normally, the markrecorded at the end of the assignment will be your final mark for the achievement and progressparts of the assignment. The code style will be manually marks later, and that mark will be uploadedto ilearn. Once the assignment has closed for all students, the automarker marks can also beuploaded to ilearn. All marks are computed to 1 decimal place as displayed in the marking reportsthat you receive from the lab command.A. Detailed marking guides for each stageWhen you download and extract the files for a stage you will find a file called markingguide.txtin the extracted files. This text file contains a detailed marking rubric for the stage.The auto marker uses this rubric to mark your submission for the stage. The marking guide includesdetailed notes that describe how each mark is calculated and what is being marked. In particular,the marking guide will tell you whether each item is marked proportionally, by error count, or as aBoolean (see Types of Achievement Marks, below).In later stages, some auto marker checks are thresholds. Threshold conditions may not contributemarks to your total, but are required for your program to be eligible to earn other marks. Themarking report will display if any threshold has failed, and it will indicate which marks aresuppressed due to the failed threshold. Thresholds and marks that require thresholds are indicatedin the marking guide marking-guide.txt. The idea behind threshold marks is that you need tohave a program which meets the basic requirements before awarding you marks for moresophisticated behaviour of your program.The marking-guide.txt file is generated by the server from configuration information that ispart of the automarking process. The marking guide itself is the same for all students. However,generating it in the server and delivering it to you in this way ensures that the marking guide isconsistent with the servers marking system.B. Types of Achievement MarksThere are three types of achievement marks, as explained in the marking-guide.txt files. Ordinary marks are proportional, computed as a percentage and scaled to the maximummark. For example, there is a mark awarded for the correctness of your output file, that iscomputed from the proportion of correct rows and the proportion of correct columns in theoutput file. After scaling according to the maximum mark, the mark is rounded down to amultiple of 0.1. For example, if the percentage mark is 98% and the mark is scaled to amaximum of 1.0, then the rounded mark would be 0.9 (not 1.0). Rounding down ensuresthat full marks are only awarded for perfect scores of 100% on the particular marking item. Error count marks deduct a fixed amount (usually 0.1 or 0.15) from the maximum mark foreach error that is counted, until the mark reaches 0.0. Error count marks are typically usedfor error checking such as checking your structure definition a fixed amount is deductedfor each error found in the definition, and the automarker gives you are hint identifying theerrors. Boolean marks are used for test conditions which are either success or failure. The mark isawarded either as the full mark or as 0.0. The full mark is awarded when the test conditionis satisfied, and 0.0 is awarded when the test fails. Boolean marks typically have small values(such as 0.1 or 0.2) and are awarded for specific tests such as ensuring that your programexits without an error status in normal operation, or that there are no memory leaks.Copyright 2020 Macquarie University.C. Maximising Your MarkHere are some hints to get the most marks in this assignment.1. Work on this assignment every week until the deadline. Dont wait until youve finished theassignments for your other units before you start this assignment. This assignment isintended to be worked on over a period of 5 weeks and almost certainly cannot becompleted in a few days.2. Achieve at least 2.0 marks in each stage of this assignment by the progress mark deadline.Progress marks reward you for consistently working on the assignment. You show that youare working consistently by achieving a mark of at least 2.0/3.0 for the next stage of theassignment each week.3. Start thinking about the next stage, and start working on it, once you have a reasonablygood mark (at least 2.0) for the earlier stages. You may have an obscure bug that costs you0.1 or 0.2 marks in the current stage, but you can earn more marks by working on the nextstage than by spending all your time trying to perfect your current stage score.4. Do your own testing as well as using the hints provided by the automarker. The automarkercan give you a general idea of your problems, but running your program yourself allows youto examine the particular mistakes that you are making.Copyright 2020 Macquarie University.The Stages of Assignment 1Stage 1: Initialising a C struct and printing it out as text [3 marks]In this stage you will declare a C data structure, create an instance of it and statically initialise it(declare it as a static or global variable and initialise it in one statement using braces). You will thenprint out the instance. This stage develops the following specific skills: Declaring a C struct. Initialising a C struct Printing various data types using printfNote: Do not use bit fields in your struct. All the data types that are specified correspond toordinary C data types.Note: The automarker checks your struct definition against expected ways of writing it andawards marks for correctness. Field names must be exactly correct. Types should be the common Clanguage data types as defined in ANSI C.ResourcesThe following Documents on iLearn may be helpful: Compile, Run, Make C Programs on Linux C Programming Notes for Data File Lab Decimal, Binary, Octal and HexC language features you may need to know: struct C data types for integers and floating point includingo different sizes of integerso signed and unsigned integerso char printf, and printf format specifiers Writing integer constants in decimal, octal and hexadecimalOther topics that you may need to understand: Binary representation of integers 2s complement representation of negative numbers Conversion between decimal, binary, octal and hexadecimalYour downloaded stage1.tar file contains the following files: filestruct-description.txt: A simple description of the fields that are in yourstruct their names and type description. initialisation-specification.txt: Specifies the initial value for each field ofyour struct. The initial value has to be formatted in a specific way in your source code thismay mean that you have to convert one representation to another. See the lab noteDecimal, Binary, Octal and Hex. Note: It makes no difference to the data that is stored insidethe computer whether you initialise the field with decimal or the equivalent hexadecimal orCopyright 2020 Macquarie University.octal. However, as an exercise, we require you to make the appropriate type conversionsand the automarker will check your code. expected-output.txt: Stage 1 expected output file. Use the example in this file towork out what formatting options to use in printf.Useful Unix commandsYou might find the following Unix system commands helpful. cat diffTaskWrite a C program that declares your particular data structure as described in the C structuredescription file. Statically1 initialise an instance of the data structure to the initial values as specifiedin the file use the data formats as specified in the file such as hexadecimal, decimal or octalconstants. In the main program, print out the data structure using printf formatting to make itexactly match the provided sample output file. Note that you may need to use various formattingoptions with printf to control the appearance of the output. You are expected to read aboutprintf and work out how to format the data so that it exactly matches the expected output.Submit your program for automatic assessment using the lab command. Your program style maybe assessed according to the coding standards in the documents Some Important Comments on CodeStyle and Systems Programming Style which are available on iLearn.Stage 2: Reading a binary data file and printing it out [3 marks]In this stage you will read a binary data file in a known format, storing the information into instancesof a C data structure which you will then print out. This stage develops the following specific skills: Reading binary data Opening and closing files Printing various data types using printf. Using a simple command-line parameter.Resources filestruct-description.txt: Describes the members of the C data struct whichcorrespond to fields in the records of the data file. input-*.bin: Sample binary input files. output-*.txt: Sample text output files corresponding to the input files.C language features you may need to know: fopen system library call to open a file, and a related call to close the file fread system library call to read binary data from a file sizeof operator in C The parameters of main() and how to access the command line parameters1 Static initialisation means to initialise the whole data structure as part of its declaration, where the fieldvalues are listed inside curly braces. Dont write separate lines of code that initialise each member of thestruct. The automarker looks specifically for the required type of initialisation.Copyright 2020 Macquarie University.Useful Unix commandsYou might find the following Unix system commands helpful. more or less diff odTaskWrite a C program that reads a file of binary data records as described in the structure descriptionfile. The program will obtain the file name as a command line parameter (see below). The programwill read and print all the records in a binary data file where each record has the format described infilestruct-description.txt. You already developed code to print out a single record instage 1, so the focus of this stage is reading a binary data file into memory.The output formatting requirements for this stage are the same as in stage 1. However, it is possiblethat you may need to modify your record printing code it could be that your printf call workedcorrectly for the single initialised record in stage 1 but it may not be correct for all the data recordsin the files. You should check the output against the expected output using diff, and improve yourprintf statement in whatever way is needed to get the correct output.Your program must accept one command-line parameter which is the name of the input file. Theautomarker will run your program many times, each time with a different input file name as theparameter, and it will compare the output of each run with the expected output. You should do thesame thing for your own testing.The fields of the records are stored using the types specified in the data file description. The fieldsare stored packed next to each other in the data file. You cannot read the entire record directly intoa C struct in one call because C inserts additional unused space between some of the fields in thestruct (this is called alignment Padding; we will discuss it later in COMP2100 lectures)2. You mustread the data record one field at a time. It is suggested to use fread to read each field.Each record that you read should be printed out as text. Your output should exactly match thesample output files.Remember that coding style is important: use good modularisation, and use header filesappropriately. Your programs style may be assessed according to the coding standards in thedocuments Some Important Comments on Code Style and Systems Programming Style.Submit your program for marking using the lab command. We may use additional data files fortesting, including files that are larger than the samples provided to you.Stage 3: Sorting a binary data file [3 marks]In this stage you will sort files of binary data in a known format. This stage develops the followingspecific skills: Reading and writing binary data files. Opening and closing files.2 The C compiler has a special way of creating structs that are packed, but this is a non-standard extension andthe automarker does not accept programs that use it.Copyright 2020 Macquarie University. Working with pointers to structures. Memory allocation, dynamically sizing an array. Using system library routines (specifically, a system library sort routine). Writing code to compare structures with a lexical sort order. Using a function pointer in C.Resources filestruct-description.txt: Describes the members of the C data structure whichcorrespond to fields in the records of the data file. filestruct-sort.txt: Specifies the sorting order. input-*.bin: Sample binary input files. output-*.bin: Sample binary output files corresponding to the input files. The outputfiles contain the same data as the input files, but the records are sorted.C language features you may need to know: fwrite system library call to write binary data to a file qsort system library call to sort data Memory allocation, and freeing memoryUseful Unix commandsYou might find the following Unix system commands helpful. od cmpTaskModify your program from stage 2 so that it reads the input file (parameter 1), storing all the recordsinto a dynamic array in memory. The program should then sort the data records and write theoutput file (parameter 2) in sorted order. The automarker will test your program by running it manytimes, each time with a dif”
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