You must start working on the projects as soon as they are assigned to detect any problems and to address them with us well before the deadline so that we have time to get back to you before the deadline.
There will be no extensions and no negotiation about project grades after the submission deadline.
Project 2: Dynamic Playlists
Congrats to everyone who finished Project 1. You can’t celebrate yet however because we have more projects for you!
Introduction
This project will test your knowledge about dynamic memory allocation and classes. While working on this project, you will realize the usefulness of dynamically allocated arrays and classes.
Work incrementally! Work through the tasks sequentially (implement and test). Only move on to a task when you are positive that the previous one has been completed correctly. Remember that the function prototypes and global-variables must be exactly as specified in this project specification. Lastly, do NOT use EOF(End of File), vector, or any library that we haven’t learned yet in class. If you don’t understand this project specification and its requirements, ask for clarification before you proceed. TEST YOUR CODE BEFORE SUBMITTING!!!
Task A: Dynamically Allocated Playlists
We will be making a playlist system to keep the order of songs. Similar to Project 1, we will be using global arrays to store song information. The difference is, these arrays are going to be dynamically allocated!
int g_curr_size = 2;
int g_number_of_songs = 0;
string *g_song_names = new string[g_curr_size];
string *g_artist_names = new string[g_curr_size];
int *g_song_durations = new int[g_curr_size];
string *g_genres = new string[g_curr_size];
Create a C++ file and add the following functions:
/*
@post : Replace the old global
dynamically allocated arrays
with new dynamically allocated
arrays of twice the size
('g_curr_size' * 2). Update
'g_curr_size' accordingly.
Make sure you copy the contents
of the older arrays. Do this
for the following global-arrays:
'g_song_names', 'g_artist_names',
'g_song_durations', 'g_genres'
*/
void allocateNew();
/*
@param : The string with the 'filename'
@post : Reads the song, artists,
song durations and genres into
the global-arrays and set the
value of 'g_number_of_songs'
to the number of songs read.
Call 'allocateNew()' to allocate
an array of larger size if the
dynamic arrays reach full
capacity.
*/
void readSongs(string filename);
Here’s an example text file:
Song Name:Artist Name-GENRE-1 mins
A Tale of 2 Citiez:Ryan Vaz-Jazz-2 mins
Don't Stop the Music:Bode Chiu-Pop-1 mins
Africa:Baolin Cheng-Rock-3 mins
Back to December:Meheraan Khan-Hiphop-3 mins
Y'all Been Warned:Tony Wang-Rnb-4 mins
Outside:Georgina Woo-Pop-12 mins
One Last Time:Kazi Mansha-Rnb-1 mins
Maps:Ashfak Uddin-Metal-2 mins
In the End:Mohammed Slim-Hiphop-301 mins
N.Y. State of Mind:Rawad Yakub-Classical-35 mins
Renegade:Zakaria Almardaee-Metal-3 mins
You Know You Like It:Justin Lau-Pop-2 mins
A Place for My Head:Bryant Zheng-Jazz-4 mins
No Title:Isabel Stec-Pop-3 mins
Example:
Calling readSongs() on the above text file will modify the global variables like this:
g_curr_size : 16
g_number_of_songs: 15
g_song_names : [ "Song Name", "A Tale of 2 Citiez", "Don't Stop the Music", "Africa",
"Back to December", "Y'all Been Warned", "Outside", "One Last Time",
"Maps", "In the End", "N.Y. State of Mind", "Renegade",
"You Know You Like It", "A Place for My Head", "No Title" ]
g_artist_names : [ "Artist Name", "Ryan Vaz", "Bode Chiu", "Baolin Cheng",
"Meheraan Khan", "Tony Wang", "Georgina Woo", "Kazi Mansha",
"Ashfak Uddin", "Mohammed Slim", "Rawad Yakub", "Zakaria Almardaee",
"Justin Lau", "Bryant Zheng", "Isabel Stec" ]
g_song_durations : [ 1, 2, 1, 3, 3, 4, 12, 1, 2, 301, 35, 3, 2, 4, 3 ]
g_genres : [ "GENRE", "Jazz", "Pop", "Rock", "Hiphop", "Rnb", "Pop", "Rnb", "Metal",
"Hiphop", "Classical", "Metal", "Pop", "Jazz", "Pop" ]
Make sure your program produces the correct output by testing the functions and global-variables using main() function.
Note: Only submit single .cpp file to gradescope.
Task B: Playlist filters
Let’s learn more about our playlists. Add and implement the following functions:
/*
@param genre : A string representing a genre
@param(&) genreCount : An integer that will keep track of the number of songs
@return : A pointer to a dynamically allocated array of strings
@post : Return a pointer to a dynamically allocated array of strings
containing the names of the songs of given 'genre' and
update 'genreCount' to be the number of songs found.
Return a pointer to an empty dynamically allocated array
if no songs are found of the given 'genre'
For example : Let's say we have the following 'g_song_names':
["Killshot", "Takeover", "Spectre", "Ether", "No Title"]
Let's say we have the following 'g_genres':
["HipHop", "HipHop", "EDM", "HipHop", "JPop"]
We try the following code with the above global-arrays:
int main(){
int count = 0;
string * genreSongs = getGenreSongs("HipHop", count);
}
In this case, 'genreSongs' will be pointing to the following:
["Killshot", "Takeover", "Ether"]
The value of 'count' will be updated to 3 because there
are three "HipHop" songs on the playlist
*/
string * getGenreSongs(string genre, int &genreCount);
/*
@param duration : The integer duration of the songs
@param(&) durationsCount : An integer that will keep track of the number of songs
@param filter : An integer(0, 1 or 2) representing the comparision filter
0 = greater-than, 1 = less-than, 2 = equal-to
@return : A pointer to a dynamically allocated array of strings
@post : Return a pointer to a dynamically allocated array of strings
of songs that are either greater-than, less-than or equal-to
the given 'duration' based on given 'filter'. Update parameter
'durationsCount' with the number of songs found. Return a
pointer to an empty dynamically allocated array if no songs
are found with the given parameters
For example : Let's say we have the following 'g_song_names':
["Major Crimes", "Never Fade Away", "Circus Minimus", "4aem", "Reaktion"]
Let's say we have the following 'g_song_durations':
[3, 4, 3, 5, 2]
We try the following code with the above global-arrays:
int main(){
int greater = 0;
int less = 0;
int equal = 0;
string * longSongs = getSongsFromDuration(3, greater, 0);
string * shortSongs = getSongsFromDuration(3, less, 1);
string * mediumSongs = getSongsFromDuration(3, equal, 2);
}
After running the above code, 'longSongs' will be:
["Never Fade Away", "4aem"]
The value of 'greater' will be 2 because there are two songs
greater than 3 mins duration
Similarly, 'shortSongs' will be:
["Reaktion"]
The value of 'less' will be 1 because there is only one song
less than 3 mins duration
Finally, 'mediumSongs' will be:
["Major Crimes", "Circus Minimus"]
The value of 'equal' will be 2 because there are 2 songs
equal to 3 mins duration
*/
string * getSongsFromDuration(int duration, int &durationsCount, int filter);
/*
@param : An integer that will keep track of unique artists
@return : A pointer to a dynamically allocated array of strings
@post : Return a pointer to a dynamically allocated array of strings
containing the names of unique artists in 'g_artist_names'
and update 'uniqueCount' parameter to be the number of
unique artists found
For example : Let's say we have the following 'g_artist_names':
["Eminem", "Eminem", "Jay Z", "Jay Z", "Nas"]
We try the following code with this 'g_artist_names':
int main(){
int count = 0;
string * uniques = getUniqueArtists(count);
}
In this case, 'uniques' will be pointing to the following:
["Eminem", "Jay Z", "Nas"]
The value of 'count' will be updated to 3 because there
are three unique artists on the playlist
*/
string * getUniqueArtists(int &uniqueCount);
/*
@return : A string with the artist with most songs in playlist
@post : Find the artist with the most songs in the playlist
If there are multiple such artists, return any one of them.
Return "NONE" if the playlist is empty
For example : Let's say we have the following 'g_artist_names':
["J. Cole", "J. Cole", "Kendrick", "Kendrick", "Kendrick"]
The favorite artist here is "Kendrick" because he has 3 songs
However, consider the following 'g_artist_names':
["J. Cole", "J. Cole", "Kendrick", "Kendrick", "Drake"]
In this case, the favorite artist is either "J.Cole" or "Kendrick"
because both artists have 2 songs which is greater than any
other artists in the playlist
*/
string getFavoriteArtist();
Note: For functions that return a pointer to a dynamic array, use g_number_of_songs as the size
Feel free to write any helper functions to make your lives easier. Test your functions thoroughly using main(). Submit a single .cpp file with the functions.
Task C: Combine
Classes are a wonderful way to group data together. Instead of using four dymanic arrays, what if we had a single dynamic array of Song objects?
In a new .cpp file, define a class called Song with the following public data members:
string name;
string artist;
int duration;
string genre;
Add the following global variables in your file:
int g_capacity = 2;
int g_size = 0;
Song *g_songs = new Song[g_capacity];
Change the functions from Task A as follows:
/*
@post : Replace the old global
dynamically allocated array
'g_songs' with new dynamically
allocated array of twice the
capacity ('g_capacity' * 2).
Update 'g_capacity' accordingly.
Make sure you copy the contents
of the old array to the new one.
*/
void allocateNew();
/*
@param : The string with the 'filename'
@post : Reads the song, artists,
song durations and genres into
the 'g_songs' and sets the
value of 'g_size' to the number
of songs read. Call 'allocateNew()'
where necessary similar to Task A.
*/
void readSongs(string filename);
Since we are using a single dynamic array of objects, the functions from task B will need to be implemented differently:
// Now returns a dynamic array of 'Song' objects instead of a 'string' objects
Song * getSongsFromDuration(int duration, int &durationsCount, int filter);
Song * getGenreSongs(string genre, int &genreCount);
// Change the implementation since we are using 'Song' class
string * getUniqueArtists(int &uniqueCount);
string getFavoriteArtist();
The functionality of the above functions remain unchanged from Task A and Task B. Take a look at Task A and B specification if necessary.
Only submit a single .cpp file to gradescope with all the functions
Credits: Genady Maryash, Yoomin Song, Sadab Hafiz, Ryan Vaz
