Assignment 0 Solution

You have been given a file “SongCSV.csv” which contains comma separated

data on separate lines. You are to read that file and create a struct for each

song that includes: Artist, Name of Song, Album Name, Duration, Year of

Release, and Hotttnesss.




For the first song in the file




1,"SOCJJDX12A8C13E745",222209,"Aswad vs. The Rhythm

Riders","ARP39OU1187FB4D543",,"West London

England",,"Aswad",0.0,258.42893,1,0.69,199.826,nan,7,0.32,"Rudeboy",0




the relevant fields are Aswad, Rudeboy, Aswad vs. The Rhythm Riders,

258.42893, 0, and nan(enter 0.0). Artist, Name of Song, and Album Name

is stored as char *,Duration is a float, Year of Release is an integer, and

Hotttnesss is a double




You will dynamically allocate memory for each struct as the file is processed.

An array of pointers to these will be managed so that searching can be

accomplished (binary search because you sorted the pointers).




You will fopen() the file, and then use the I/O operations from Chapter 5

(standard library) in Stevens to process the file (fgets(), fclose(), feof() etc ).

You may use strtok_r() from the string libraries, as well as atoi() and atof().




Think of this program as a step towards something larger. Demonstrate that

your program works by searching the array for a given song and outputting

the struct data. Make a typescript (use utility ‘script’) of this performance

by searching with the following keys:




For the output you may use fprintf() to stdout. We will test this ourselves,

but for the moment take user input (the song name) and use it to search the

sorted structs using … ! … binary search.




This assignment will ultimately be on the jazz server … a work in progress.

I hope we can have all of this taken care of quite soon.




Basic Algorithm Flow:




1Open the csv file




2 Extract lines, one at a time.




Put relevant fields (see above) into a struct which is then put into an

array of structs. Please note that you are required to allocate memory

for structs dynamically.




3 Sort the array of structs by song name. (You may have been doing this in

step 2)




4) Create user interface to search for songs by song name Display relevant

data to user in a neat format Exit only when user enters ZZZ (not 'Quit' or

'q' or 'Q' or 'exit' or 'Exit' or 'EXIT' or 'Leave" or anything other than ZZZ)




We have provided a make file for you and a sample testing input file (we

will cleverly use a different one for actual testing). If your program does not

work with 'make && make test' we will not be able to test your program,

and you will not like your grade.




Also, would you please push only the source code and typescript of

performance. Please do not push back the various files that have been

provided to you (e.g. syllabus).




Discussion




The intent of this assignment and the next is to immerse you in the C / Unix

system programming environment with the good, bad, and ugly of it all. A

number of issues are worth mention (in no particular order here).




0) YOU MUST HAVE A LAPTOP RUNNING UNIX. Although you can

survive with a VM , it offends me that you don’t have something more

permanent – just old fashioned. Have the wizards help you dual boot.

Bring your machine to class.




I) C and standard library issues

1) Pointers – love the asterisk. Know how to declare, instantiate i.e.

make the pointer point somewhere, dereference and assign

values to the ‘pointee’. Understand that because C as a language

is limited the ‘*’ shows up in parameter passing, strings (char *),

and function returns of compound data structures (arrays,

structs). Understand that arrays are synonymous with pointers

and that pointers can be subscripted cuz why not ?

2) dynamically allocated memory via malloc(), calloc(), realloc()

requires using pointers.

3) Structs and pointers – fields are referenced with . or - depending

on how you have access to the struct. Structs can be copied

wholesale.

4) The string functions all use char * references with a null

terminator. strlen() does not count the null but allocating memory

for a strncpy() requires that extra byte. Be careful with strtok_r().

Use the ‘n’ versions of string functions (strncpy() vs strcpy() ),

Use the _r versions (‘reentrant) of functions.

5) Standard library I/O use the ‘f’ library routines built upon the

non-f system calls: fopen() vs open(), buffered streams vs

unbuffered references via file descriptors; formatted fprintf() vs

unformatted write().




II) From Source to Executable the Unix Way

The steps of creating programs: cpp, gcc (translate), gcc (load via

ld), and then execute. Make files automate the above. Source code is

‘pre-processed’ to take advantage of #include directives and good

software practice

III) Use The Utilities

Use utilities such as script, make, valgrind , and gdb – NOW. Your

life will be easier if you invest in minimal mastery of these tools.

Make automates command line source code management. Valgrind

insures you don’t have pointers going astray and often reveals

bugs. Gdb allows you a debugger. Script lets you document

program behavior. Each has its idiosyncracies.










IV) The Assumed Stevens Working Environment

You may use an IDE if you wish but we will assume command line

capability. Use gedit for screen editing capabilities. Be able to

navigate and reproduce Stevens code.

The Stevens environment. “apue.h” and the companion source code

“error.c” are used throughout Stevens’ source code. Use these

because then you can reproduce his examples. I will provide copies

of apue.h, error.c, and all of the source code in the text. You must

test all system call return values so use Stevens’ error routines as a

habit. See Ch1 for the errno, perror() scheme provided in all Unix

environments.