Question

Hi I've a problem with this code. When I add more than 1 song to the list, it doesn't show the first one, only shows the latest one, when I called the function displaysong, let's say when you add 2 songs ID 1 then ID 2, it shows only ID 1. Can you fix it.  Everything else is fine..

#include <iostream>

#include<string>

using namespace std;

//class Song

class Song{

private:

int songID;

string title;

string artist;

string album;

int year;

public:

Song(); //default constructor, set string variables to "" and set integer variables to 0

Song(int aID, string aTitle, string anArtist, string anAlbum, int aYear); //parametrized constructor

int getSongID()const; // return value song ID

string getTitle()const; // return value title

string getArtist()const; // return value artist

string getAlbum()const; // return value album

int getYearReleased()const; // return value year

void setSongID(int newSongID); //set the songID to newSongID

void setTitle(string newTitle); //set the title to newTitle

void setArtist(string newArtist); //set the artist to newArtist

void setAlbum(string newAlbum); //set album to newAlbum

void setYear(int newYear); //set year to newYear

};

struct node{

Song song;

node *next;

};

//insert your code for all the constructs and member functions of Song class here

//For example, this is the code (incomplete) for the default constructor of the class

Song::Song()

{

songID = 0;

title="";

artist="";

album="";

year=0;

//insert code here

}

Song::Song(int aID, string aTitle, string anArtist, string anAlbum, int aYear){

songID=aID;

title=aTitle;

artist=anArtist;

album=anAlbum;

year=aYear;

}

int Song::getSongID()const{

return songID;

}

string Song::getTitle()const{

return title;

}

string Song::getAlbum()const{

return album;

}

string Song::getArtist()const{

return artist;

}

int Song::getYearReleased()const{

return year;

}

void Song::setSongID(int newSongID){

songID= newSongID;

}

void Song::setTitle(string newTitle){

title= newTitle;

}

void Song::setArtist(string newArtist){

artist = newArtist;

}

void Song::setAlbum(string newAlbum){

album=newAlbum;

}

void Song::setYear(int newYear){

year=newYear;

}

//Complete the code for the following functions

void displayList(node** head);

void displaySong(node** head, int ID);

void insertNewSong(node** head,Song newSong);

int main(int argc, const char * argv[]) {

int choice;

node * list=NULL;

Song newSong;

int newSongID;

string newTitle;

string newArtist;

string newAlbum;

int newYear;

int id;

do

{

cout << endl

<< "***** My Song List *****" << endl

<< " 1 - Display List" << endl

<< " 2 - Display a Song" << endl

<< " 3 - Insert new Song" << endl

<< " 4 - Exit." << endl

<< " Enter your choice and press return: ";

cin >> choice;

switch (choice)

{

case 1:

//call the function displayList to display the song that appears in the list

   displayList(&list);

break;

case 2:

{

cout << endl

<< "Enter the ID of the song that you would like to display!" << endl;

cin >> id;

//call displaySong functioin to display the name of the song based on

displaySong(&list, id);

break;

}

case 3:

{

cout << endl

<< "Enter information for your new song!" << endl;

cout << "Song ID : " ;

cin.ignore();

cin >> newSongID;

newSong.setSongID(newSongID);

cout << "Title : " ;

cin.ignore();

getline(cin, newTitle);

newSong.setTitle(newTitle);

cout << "Artist : " ;

getline(cin, newArtist);

newSong.setArtist(newArtist);

cout << "Album : " ;

getline(cin,newAlbum);

newSong.setAlbum(newAlbum);

cout << "Year : " ;

cin >> newYear;

newSong.setYear(newYear);

//call insertNewSong function to insert a new song to the list

//the new song should be added to the FRONT of the list

   insertNewSong(&list,newSong);

cout << "New song is added!!!" << endl;

break;

}

case 4:

cout << "End of Program.\n";

break;

default:

cout << "Not a Valid Choice. \n"

<< "Choose again.\n";

break;

}

}while (choice !=4);

return 0;

}

void insertNewSong(node** head,Song newSong){

node * temp= new node;

temp->song= newSong;

temp->next= *head;

*head=temp;

//add your code

}

void displayList(node ** head)

{

node*temp;

temp =*head;

while(temp!=NULL){

//temp->getSongID();

cout<<" Title:" <<temp->song.getTitle()<<endl;

cout<<" Artist:"<<temp->song.getArtist()<<endl;

cout<<" Album:"<<temp->song.getAlbum()<<endl;

cout<<"year:"<<temp->song.getYearReleased()<<endl;

temp=temp->next;

if(temp==NULL){

cout<<"end of the list"<<endl;

return;

}

}

if(temp==NULL){

cout<<" list is empty "<<endl;

}

}

void displaySong(node** head, int ID){

node*temp;

temp =*head;

while(temp!=NULL){

if(ID==temp->song.getSongID()){

cout<<" Title:" <<temp->song.getTitle()<<endl;

cout<<" Artist:"<<temp->song.getArtist()<<endl;

cout<<" Album:"<<temp->song.getAlbum()<<endl;

cout<<"year:"<<temp->song.getYearReleased()<<endl;

}

else{

cout<<" song ID not found "<<endl;

}

temp=temp->next;

return;

}

if(temp==NULL){

cout<<" list is empty"<<endl;

}

}

Answer 1

In the given code newSong variable(Song newSong;) is declared at the top in the main function and object is created when main is loaded. This way there is one object created.

So when case 3 executed again and again same object value is updated.

We should declare variable inside Case 3.

Below is updated code

#include <iostream>

#include<string>

using namespace std;

//class Song

class Song {

private:

int songID;

string title;

string artist;

string album;

int year;

public:

Song(); //default constructor, set string variables to "" and set integer variables to 0

Song(int aID, string aTitle, string anArtist, string anAlbum, int aYear); //parametrized constructor

int getSongID() const; // return value song ID

string getTitle() const; // return value title

string getArtist() const; // return value artist

string getAlbum() const; // return value album

int getYearReleased() const; // return value year

void setSongID(int newSongID); //set the songID to newSongID

void setTitle(string newTitle); //set the title to newTitle

void setArtist(string newArtist); //set the artist to newArtist

void setAlbum(string newAlbum); //set album to newAlbum

void setYear(int newYear); //set year to newYear

};

struct node {

Song song;

node * next;

};

//insert your code for all the constructs and member functions of Song class here

//For example, this is the code (incomplete) for the default constructor of the class

Song::Song()

{

songID = 0;

title = "";

artist = "";

album = "";

year = 0;

//insert code here

}

Song::Song(int aID, string aTitle, string anArtist, string anAlbum, int aYear) {

songID = aID;

title = aTitle;

artist = anArtist;

album = anAlbum;

year = aYear;

}

int Song::getSongID() const {

return songID;

}

string Song::getTitle() const {

return title;

}

string Song::getAlbum() const {

return album;

}

string Song::getArtist() const {

return artist;

}

int Song::getYearReleased() const {

return year;

}

void Song::setSongID(int newSongID) {

songID = newSongID;

}

void Song::setTitle(string newTitle) {

title = newTitle;

}

void Song::setArtist(string newArtist) {

artist = newArtist;

}

void Song::setAlbum(string newAlbum) {

album = newAlbum;

}

void Song::setYear(int newYear) {

year = newYear;

}

//Complete the code for the following functions

void displayList(node ** head);

void displaySong(node ** head, int ID);

void insertNewSong(node ** head, Song newSong);

int main(int argc,
const char * argv[]) {

int choice;

node * list = NULL;

int newSongID;

string newTitle;

string newArtist;

string newAlbum;

int newYear;

int id;

do

{

cout << endl

<<
"***** My Song List *****" << endl

<<
" 1 - Display List" << endl

<<
" 2 - Display a Song" << endl

<<
" 3 - Insert new Song" << endl

<<
" 4 - Exit." << endl

<<
" Enter your choice and press return: ";

cin >> choice;

switch (choice)

{

case 1:

//call the function displayList to display the song that appears in the list

displayList( & list);

break;

case 2:

{

cout << endl

<<
"Enter the ID of the song that you would like to display!" << endl;

cin >> id;

//call displaySong functioin to display the name of the song based on

displaySong( & list, id);

break;

}

case 3:

{
Song newSong;

cout << endl

<<
"Enter information for your new song!" << endl;

cout << "Song ID : ";

cin.ignore();

cin >> newSongID;

newSong.setSongID(newSongID);

cout << "Title : ";

cin.ignore();

getline(cin, newTitle);

newSong.setTitle(newTitle);

cout << "Artist : ";

getline(cin, newArtist);

newSong.setArtist(newArtist);

cout << "Album : ";

getline(cin, newAlbum);

newSong.setAlbum(newAlbum);

cout << "Year : ";

cin >> newYear;

newSong.setYear(newYear);

//call insertNewSong function to insert a new song to the list

//the new song should be added to the FRONT of the list

insertNewSong( & list, newSong);

cout << "New song is added!!!" << endl;

break;

}

case 4:

cout << "End of Program.\n";

break;

default:

cout << "Not a Valid Choice. \n"

<<
"Choose again.\n";

break;

}

} while (choice != 4);

return 0;

}

void insertNewSong(node ** head, Song newSong) {

node * temp = new node;

temp - > song = newSong;

temp - > next = * head;

* head = temp;

//add your code

}

void displayList(node ** head)

{

node * temp;

temp = * head;

while (temp != NULL) {

//temp->getSongID();

cout << " Title:" << temp - > song.getTitle() << endl;

cout << " Artist:" << temp - > song.getArtist() << endl;

cout << " Album:" << temp - > song.getAlbum() << endl;

cout << "year:" << temp - > song.getYearReleased() << endl;

temp = temp - > next;

if (temp == NULL) {

cout << "end of the list" << endl;

return;

}

}

if (temp == NULL) {

cout << " list is empty " << endl;

}

}

void displaySong(node ** head, int ID) {

node * temp;

temp = * head;

while (temp != NULL) {

if (ID == temp - > song.getSongID()) {

cout << " Title:" << temp - > song.getTitle() << endl;

cout << " Artist:" << temp - > song.getArtist() << endl;

cout << " Album:" << temp - > song.getAlbum() << endl;

cout << "year:" << temp - > song.getYearReleased() << endl;

} else {

cout << " song ID not found " << endl;

}

temp = temp - > next;

return;

}

if (temp == NULL) {

cout << " list is empty" << endl;

}

}