Question

Please help! I created a DMM program in C++ that stores a file into a doubly linked list. I created a function that loads the file.csv into a linked list which works fine and I need help on writing that file into the same file.. When I compile the store function, it just writes random numbers ex( 0:1875941888 -1 0).

What must Store do?

The store command writes the current records, in the dynamic doubly linked list, to the musicPlayList.csv file. The store will completely overwrite the previous contents in the file.

My code:

----------------------LIST.CPP

void List::load(fstream& fileStream)

{

    char delim1 = ',';

    char delim2 = ':';

    while (!fileStream.eof())

    {

        Record rec;

        getline(fileStream, rec.artist, delim1);

        getline(fileStream, rec.album,delim1);

        getline(fileStream, rec.song, delim1);

        getline(fileStream, rec.genre, delim1);

        fileStream >> rec.length.minutes >> delim2;

        fileStream >> rec.length.seconds >> delim1;

        fileStream >> rec.num_plays >> delim1;

        fileStream >> rec.rating;

        addEnd(rec);

        cout << rec.artist << ' ' << rec.album << ' ' << rec.song <<

            ' ' << rec.genre << ' ' << rec.length.minutes << ':' << rec.length.seconds

        << ' ' << rec.num_plays << ' ' << rec.rating;  

    }

    cout << '\n';

}

void List::addEnd(Record data)

{

    if (m_head == nullptr)

    {

        m_head = m_tail = new ListNode(data,nullptr,nullptr);

    }

    else // not empty

    {

       m_tail = new ListNode(data, nullptr, m_tail);

       m_tail->prev->next = m_tail;

    }

    ++m_size;

}

void List::store(fstream& fileStream)

{

    Record rec;

    ListNode* nodePtr = m_head;

    // while(nodePtr->next != nullptr)

    // {

    //     nodePtr = nodePtr->next;

    // }

    // while (nodePtr->prev != nullptr)

    // {

    if (nodePtr->next == nullptr)

    {

        return;

    }

        fileStream.open("musicPlayList.txt", ios::out);

        fileStream << rec.artist << ' ' << rec.album << ' ' << rec.song

                   << ' ' << rec.genre << ' ' << rec.length.minutes << ':'

                   << rec.length.seconds << ' ' << rec.num_plays << ' '

                   << rec.rating;  

        //nodePtr = nodePtr->prev;

}

------------------------MAIN.CPP

#include <iostream>

#include <string>

#include <fstream>

#include "list.h"

using namespace std;

int main()

{

    List myList;

    fstream readFile;

    readFile.open("musicPlayList.csv", ios::in);

    if (readFile.fail())

    {

        cout << "Error opening file!\n";

        exit(1);

    }

    int menu;

    do

    {

         myList.menu();

        //menu = myList.getChoice(1, 11);

        cout << "Enter a menu: ";

        cin >> menu;

        if(menu == 1)

        {

            myList.load(readFile);

            readFile.close();

        }

        if(menu == 2)

        {

            myList.store(readFile);

            readFile.close();

        }

    return 0;

}

------------------------ list.h

#ifndef LIST_H

#define LIST_H

#include <iostream>

#include <string>

#include <fstream>

#include <cstring>

using namespace std;

struct Duration

{

  unsigned int seconds;

  unsigned int minutes;

};

struct Record

{

    string artist;

    string album;

    string song;

    string genre;

    Duration length; // the song length

    int num_plays; //times played

    int rating; //rating 1-5

};

struct ListNode

{

    Record data;

    ListNode* next;

    ListNode* prev;

    ListNode() {};

    ListNode(Record data1, ListNode* next1=nullptr, ListNode* prev1=nullptr)

    {

        data = data1;

        next = next1;

        prev = prev1;

    }

};

class List

{

public:

    // Adds an element to the end of the list

    void addEnd(Record data);

    void menu();

    void load(fstream& fileStream);

    void store(fstream& fileStream);

    // Default constructor to initialize

    List();

    ~List();

private:

    ListNode* m_head;  // points to the head of the list

    ListNode* m_tail;  // points to the end of the list

    // tracks the number of elements

    int m_size;

};

#endif

------------------------- musicPlatList.csv

Taylor Swift,1989,Shake it Off,Pop,3:35,12,3
Disturbed,THE SICKNESS,Down With The Sickness,Hard Rock,4:39,8,4
Drake,NOTHING WAS THE SAME,Own It,Rap,3:23,3,3
Disturbed,ASYLUM,Asylum,Hard Rock,4:36,2,4
Drake,YOU WELCOME,The Motto,Rap,4:13,7,4
Christina Perri,HEAD OF HEART,Trust,Pop,2:35,3,5
Justin Bieber,PURPOSE,No Sense,Pop,4:12,6,1
Eminem,SHADYXV,Vegas,Rap,3:37,8,3
Adele,25,Remedy,Pop,4:11,24,4
Disturbed,INDESTRUCTIBLE,The Night,Hard Rock,4:46,7,3
Taylor Swift,RED,Stay Stay Stay,Pop,4:42,5,1
Garth Brooks,FRESH HORSES,The Old Stuff,Country,2:57,11,2
Nirvana,NEVERMIND,Come As You Are,Grunge,3:38,5,4
Eminem,8 Mile,Lose Yourself,Rap,5:24,12,5
Five Finger Death Punch,American Capitalist,Back For More,Hard Rock,2:34,8,4
Disturbed,INDESTRUCTIBLE,Indestructible,Hard Rock,4:38,11,5

Answer 1

Please let me know if you need more information :-

======================

#include <iostream>

#include "list.h"

#include <fstream>

using namespace std;

int main()

{

fstream readFile;

readFile.open("musicPlayList.txt", ios::in);

if (readFile.fail())

{

cout << "Error opening file!\n";

exit(1);

}

int menu;

List myList; //<=== This is the right position for your list reference.

do

{

//List myList; <==== it should not be here. when loops comes back here your list again will become empty or null.

myList.menu();

cout << "Enter a menu: ";

cin >> menu;

if(menu == 1)

{

myList.load(readFile);
readFile.close();

}

if(menu == 2)

{

myList.store(readFile);

readFile.close();

}

if(menu == 3)

{

myList.displayList();

}

} while(menu != 99);

return 0;

}

===

list.cpp

===

#include "list.h"

#include <iostream>

#include <fstream>

using namespace std;

List::List()

{

m_head = nullptr;

m_tail = m_head;

m_size = 0;

}

void List::menu()

{

cout << "[ 1 ] Load [ 7 ] Delete\n"

<< "[ 2 ] Store [ 8 ] Insert\n"

<< "[ 3 ] Display [ 9 ] Sort\n"

<< "[ 4 ] Edit [ 10 ] Reverse\n"

<< "[ 5 ] Rate [ 11 ] Shuffle\n"

<< "[ 6 ] Play [ 99 ] Exit\n";

}

void List::load(fstream& fileStream)

{

char delim = ',';

char delim2 = ':';

while(!fileStream.eof())

{

Record rec;

string dummy="";

getline(fileStream, rec.artist, delim);

getline(fileStream, rec.album, delim);

getline(fileStream, rec.song, delim);

getline(fileStream, rec.genre, delim);

fileStream >> rec.length.minutes >> delim2;

fileStream >> rec.length.seconds >> delim;

fileStream >> rec.num_plays >> delim;

fileStream >> rec.rating;

addEnd(rec);

}

}

void List::addEnd(Record data)

{

if (m_head == nullptr)

{

m_head = m_tail = new ListNode(data,nullptr,nullptr);

}

else // not empty

{

m_tail = new ListNode(data, nullptr, m_tail);

m_tail->prev->next = m_tail;

}

// displayList();

++m_size;

}

void List::store(fstream& fileStream)

{

Record rec;

ListNode* nodePtr = m_head;

fileStream.open("musicPlayList.txt", ios::out);

if (nodePtr == nullptr)

{

return;

}

while(nodePtr != nullptr)

{

rec = nodePtr->data;

fileStream << rec.artist << ' ' << rec.album << ' ' << rec.song

<< ' ' << rec.genre << ' ' << rec.length.minutes << ':'

<< rec.length.seconds << ' ' << rec.num_plays << ' '

<< rec.rating; ////Here you must change the ' ' ==> with comma if you want the file to be written with ',' .

nodePtr = nodePtr->next;

}

}

void List::displayList()

{

ListNode* nodePtr = m_head;

if (nodePtr == nullptr)

{

return;

}

while(nodePtr != nullptr)

{

cout << nodePtr->data.artist << ' ' << nodePtr->data.album << ' ' << nodePtr->data.song

<< ' ' << nodePtr->data.genre << ' ' << nodePtr->data.length.minutes << ':'

<< nodePtr->data.length.seconds << ' ' << nodePtr->data.num_plays << ' '

<< nodePtr->data.rating;

nodePtr = nodePtr->next;

}

cout << "\n";

}

List::~List()

{

while(m_tail->prev != nullptr)

{

m_tail = m_tail->prev;

delete m_tail->next;

}

delete m_tail;

m_tail = nullptr;

m_head = nullptr;

}

====

list.h

====

#include <iostream>

#include<string>

using namespace std;

struct Duration

{

unsigned int seconds;

unsigned int minutes;

};

struct Record

{

string artist;

string album;

string song;

string genre;

Duration length; // the song length

int num_plays; //times played

int rating; //rating 1-5

};

struct ListNode

{

Record data;

ListNode* next;

ListNode* prev;

ListNode() {};

ListNode(Record data1, ListNode* next1=nullptr, ListNode* prev1=nullptr)

{

data = data1;

next = next1;

prev = prev1;

}

};

class List

{

public:

// Adds an element to the end of the list

void addEnd(Record data);

void menu();

void load(fstream& fileStream);

void store(fstream& fileStream);

void displayList();

// void searchList();

// Default constructor to initialize

List();

~List();

private:

ListNode* m_head; // points to the head of the list

ListNode* m_tail; // points to the end of the list

// tracks the number of elements

// currently present in the list

int m_size;

};

====

OUTPUT:-

====

[ 1 ] Load [ 7 ] Delete
[ 2 ] Store [ 8 ] Insert
[ 3 ] Display [ 9 ] Sort
[ 4 ] Edit [ 10 ] Reverse
[ 5 ] Rate [ 11 ] Shuffle
[ 6 ] Play [ 99 ] Exit
Enter a menu: 1
[ 1 ] Load [ 7 ] Delete
[ 2 ] Store [ 8 ] Insert
[ 3 ] Display [ 9 ] Sort
[ 4 ] Edit [ 10 ] Reverse
[ 5 ] Rate [ 11 ] Shuffle
[ 6 ] Play [ 99 ] Exit
Enter a menu: 3
Taylor Swift 1989 Shake it Off Pop 3:35 12 3
Disturbed THE SICKNESS Down With The Sickness Hard Rock 4:39 8 4
Drake NOTHING WAS THE SAME Own It Rap 3:23 3 3
Disturbed ASYLUM Asylum Hard Rock 4:36 2 4
Drake YOU WELCOME The Motto Rap 4:13 7 4
Christina Perri HEAD OF HEART Trust Pop 2:35 3 5
Justin Bieber PURPOSE No Sense Pop 4:12 6 1
Eminem SHADYXV Vegas Rap 3:37 8 3
Adele 25 Remedy Pop 4:11 24 4
Disturbed INDESTRUCTIBLE The Night Hard Rock 4:46 7 3
Taylor Swift RED Stay Stay Stay Pop 4:42 5 1
Garth Brooks FRESH HORSES The Old Stuff Country 2:57 11 2
Nirvana NEVERMIND Come As You Are Grunge 3:38 5 4
Eminem 8 Mile Lose Yourself Rap 5:24 12 5
Five Finger Death Punch American Capitalist Back For More Hard Rock 2:34 8 4
Disturbed INDESTRUCTIBLE Indestructible Hard Rock 4:38 11 5
[ 1 ] Load [ 7 ] Delete
[ 2 ] Store [ 8 ] Insert
[ 3 ] Display [ 9 ] Sort
[ 4 ] Edit [ 10 ] Reverse
[ 5 ] Rate [ 11 ] Shuffle
[ 6 ] Play [ 99 ] Exit
Enter a menu: 2
[ 1 ] Load [ 7 ] Delete
[ 2 ] Store [ 8 ] Insert
[ 3 ] Display [ 9 ] Sort
[ 4 ] Edit [ 10 ] Reverse
[ 5 ] Rate [ 11 ] Shuffle
[ 6 ] Play [ 99 ] Exit
Enter a menu: 99

===

==

==

Please let me know if you need more information.

==

Thanks