help me with this single linked list

[anitaNg]

what is wrong with my code?i cant figure it out.

#include<iostream.h>
#include<stdlib.h>
#include<stdio.h>


#define MAX 50

struct Node
{
	char judul[MAX];
	char pengarang[MAX];
	int harga;
	Node* nextPtr;
};


Node* makeNode(char judul[], char pengarang[], int harga)
{
	Node* newNodePtr = (Node*)malloc(sizeof(Node));
	if(newNodePtr == NULL)
	{
		cout << "Out of Memory" << endl;
		exit(1);
	}
	else
	{
		newNodePtr->judul = judul;		
		newNodePtr->pengarang = pengarang;	
		newNodePtr->harga = harga;
		newNodePtr->nextPtr = NULL;
	}
	return newNodePtr;
}

void insertNode(char judul[],char pengarang[],int harga)
{

	Node* headPtr = NULL;
	Node* rearPtr = NULL;
	Node* newNodePtr = NULL;
	Node* myPtr = NULL;
	Node* newPtr = NULL;
	Node* prevPtr = NULL;

	
				if(headPtr == NULL)
				{
					headPtr= makeNode(judul,pengarang,harga);
					
					rearPtr = headPtr;
					myPtr = headPtr;

				
				}
				else if(judul <= headPtr->judul && pengarang <= headPtr->pengarang)	
				{
						myPtr = headPtr;
						headPtr = makeNode(judul,pengarang,harga);
						
						headPtr->nextPtr = myPtr;

					
				}
				
				else if(judul >= rearPtr->judul && pengarang >= rearPtr->pengarang)		
				{
					myPtr = rearPtr;
					rearPtr = makeNode(judul,pengarang,harga);
					
					myPtr->nextPtr = rearPtr;

				
				}				
				else
				{					
					newPtr = makeNode(judul,pengarang,harga);
					
					myPtr = headPtr;
					while(judul >= myPtr->judul)		
					{
						prevPtr = myPtr;
						myPtr = myPtr->nextPtr;
					}
					prevPtr->nextPtr = newPtr;
					newPtr->nextPtr = myPtr;
																
				}
}

void deleteNode(char judul[])
{
	Node* headPtr = NULL;
	Node* rearPtr = NULL;
	Node* newNodePtr = NULL;
	Node* myPtr = NULL;
	Node* newPtr = NULL;
	Node* prevPtr = NULL;
			
			if(headPtr->judul == judul)			
			{
				myPtr=headPtr;
				headPtr=headPtr->nextPtr;
				cout << "Data " << judul << " telah dihapus" << endl;
				free(myPtr);
			}


			else
			{
				myPtr = headPtr->nextPtr;
				prevPtr = headPtr;
				while(myPtr != NULL && myPtr->judul != judul)  //?
				{
					myPtr=myPtr->nextPtr;
					prevPtr=prevPtr->nextPtr;
				}
				if(myPtr==NULL)
				{
					cout << "Element not found" << endl << endl;
				}
				else
				{
					prevPtr->nextPtr=myPtr->nextPtr;
					cout << "Data " << judul << " telah dihapus" << endl;
					free(myPtr);
				}
				

			}

		

}

void display()
{
	Node* headPtr = NULL;
	Node* rearPtr = NULL;
	Node* newNodePtr = NULL;
	Node* myPtr = NULL;
	Node* newPtr = NULL;
	Node* prevPtr = NULL;

			cout << endl << endl;
			cout << "Data Anda: " << endl;
			cout << "Judul" << "\t" << "Pengarang" << "\t" << "Harga" << endl ;
			myPtr = headPtr;
			while (myPtr != NULL)
			{
					cout << "  " << myPtr->judul << "\t" ;
					cout << "    " << myPtr->pengarang << "\t" ;
					cout << "\t" << myPtr->harga  ;
					myPtr = myPtr->nextPtr;
					cout << endl;
			}
			cout << endl;
}


void main()
{
	char judul[MAX];
	char pengarang[MAX];
	int harga;
	int choice ;
	

	while(choice != 0)
	{
		cout << "Insert your choice : " << endl;
		cout << "(1) Insert "  << "\t" << " (3) Display " << endl;
		cout << "(2) Delete "  << "\t" << " (0) Exit " << endl;
	
		cout << "Your choice : ";
		cin >> choice;
		cout << endl;

		if(choice == 1)		//insert
		{
			cout << "Masukkan Judul : ";
			cin >> judul;		
			cout << "Masukkan Nama Pengarang : ";
			cin >> pengarang;
			cout << "Masukkan Harga : ";
			cin >> harga;
			insertNode(judul,pengarang,harga);
			display();
		}
						
		if(choice == 2)		//delete
		{
			cout << "Delete Data : ";
			cin >> judul;

			deleteNode(judul);
			display();
		}
		if(choice == 3)   //display
		{
			display();
		}
		if(choice == 4)   //Exit
		{
			cout << "Thank You" << endl;
		}
	}
	
	
}

i want to type in more than 1 char. but i can't find the way to solve it.
fyi, i'm using visual studio C++ 6 :)
thanks, any helps will be appreciated

[jonsca]

Line 28:

newNodePtr->pengarang = pengarang;

You are only copying the pointer over, not the contents of the string. Use strcpy(newNodePtr->pengarang,pengarang); instead (or better, since you don't know how large your source string is, use strncpy).

[anitaNg]

wow thanks. it helped so much. :)
but there's one problem. the data didn't sort alphabetically as it used to be. any idea?

[jonsca]

You reset head pointer to null on line 38. Why? It's guaranteed to follow the path of that first if statement each time, and what if there already is a valid head pointer? (hint pass it into your function) That may not be the problem, but it's one of the first places I would look.

[anitaNg]

oh yeah i didn't realize about that, thanks! :)
but still. it didn't sort and the delete function seems not to work.

[jonsca]

If you don't rework insertNode() like I was saying, of course it's not going to sort. Get the insert procedure correct and the deleting will be trivial. Do you have access to a debugger? (I don't remember how good the one was in VC6). You need to step through your code and watch as the nodes are added. I've given you a pointer, but I'm not going to rewrite it for you. Take another crack at it and post back your new insertNode() function.

[anitaNg]

okay i have changed the insertNode() and deleteNode()and overall it seems to workout,thanks to you :) but there's one more problem. when i debug it, and input more than 4 times, the program stops. any idea?

btw, here are the program

#include<iostream.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>



#define MAX 50

struct Node
{
	char judul[MAX];
	char pengarang[MAX];
	int harga;
	Node* nextPtr;
};

	Node* headPtr = NULL;
	Node* rearPtr = NULL;
	Node* newNodePtr = NULL;
	Node* myPtr = NULL;
	Node* newPtr = NULL;
	Node* prevPtr = NULL;

Node* makeNode(char judul[], char pengarang[], int harga)
{
	Node* newNodePtr = (Node*)malloc(sizeof(Node));
	if(newNodePtr == NULL)
	{
		cout << "Out of Memory" << endl;
		exit(1);
	}
	else
	{
		strcpy(newNodePtr->judul,judul);		
		strcpy(newNodePtr->pengarang,pengarang);	
		newNodePtr->harga = harga;
		newNodePtr->nextPtr = NULL;
	}
	return newNodePtr;
}

void insertNode(char judul[],char pengarang[],int harga)
{

				if(headPtr == NULL)
				{
					headPtr= makeNode(judul,pengarang,harga);		
					rearPtr = headPtr;
					myPtr = headPtr;
				
				}
				else if(strcmp(judul,headPtr->judul)<=0)	
				{
						myPtr = headPtr;
						headPtr = makeNode(judul,pengarang,harga);						
						headPtr->nextPtr = myPtr;
					
				}
				
				else if(strcmp(judul,rearPtr->judul)>=0)		
				{
					myPtr = rearPtr;
					rearPtr = makeNode(judul,pengarang,harga);				
					myPtr->nextPtr = rearPtr;				
				}				
				else
				{					
					newPtr = makeNode(judul,pengarang,harga);
					
					myPtr = headPtr;
					while(judul >= myPtr->judul)		
					{
						prevPtr = myPtr;
						myPtr = myPtr->nextPtr;
					}
					prevPtr->nextPtr = newPtr;
					newPtr->nextPtr = myPtr;																
				}

				cout << endl << endl;
				//display
				cout << "Data Anda: " << endl;
				cout << "Judul" << "\t" << "Pengarang" << "\t" << "Harga" << endl ;
				myPtr = headPtr;
				while (myPtr != NULL)
				{
						cout << "  " << myPtr->judul << "\t" ;
						cout << "    " << myPtr->pengarang << "\t" ;
						cout << "\t" << myPtr->harga  ;
						myPtr = myPtr->nextPtr;
						cout << endl;
				}
				cout << endl;
}

void deleteNode(char judul[])
{
	
			
			if(strcmp(headPtr->judul,judul)==0)			
			{
				myPtr=headPtr;
				headPtr=headPtr->nextPtr;
				cout << "Data " << judul << " telah dihapus" << endl;
				free(myPtr);
			}


			else
			{
				myPtr = headPtr->nextPtr;
				prevPtr = headPtr;
				while(myPtr != NULL && myPtr->judul != judul)  //?
				{
					myPtr=myPtr->nextPtr;
					prevPtr=prevPtr->nextPtr;
				}
				if(myPtr==NULL)
				{
					cout << "Element not found" << endl << endl;
				}
				else
				{
					prevPtr->nextPtr=myPtr->nextPtr;
					cout << "Data " << judul << " telah dihapus" << endl;
					free(myPtr);
				}
				

			}
			//display
			cout << endl << endl;
			cout << "Data Anda: " << endl;
			cout << "Judul" << "\t" << "Pengarang" << "\t" << "Harga" << endl ;
			myPtr = headPtr;
			while (myPtr != NULL)
			{
					cout << "  " << myPtr->judul << "\t" ;
					cout << "    " << myPtr->pengarang << "\t" ;
					cout << "\t" << myPtr->harga  ;
					myPtr = myPtr->nextPtr;
					cout << endl;
			}
			cout << endl;

		

}




void main()
{
	char judul[MAX];
	char pengarang[MAX];
	int harga;
	int choice ;
	

	while(choice != 0)
	{
		cout << "Insert your choice : " << endl;
		cout << "(1) Insert "  << "\t" << " (3) Display " << endl;
		cout << "(2) Delete "  << "\t" << " (0) Exit " << endl;
	
		cout << "Your choice : ";
		cin >> choice;
		cout << endl;

		if(choice == 1)		//insert
		{
			cout << "Masukkan Judul : ";
			cin >> judul;		
			cout << "Masukkan Nama Pengarang : ";
			cin >> pengarang;
			cout << "Masukkan Harga : ";
			cin >> harga;
			insertNode(judul,pengarang,harga);
			
		}
						
		if(choice == 2)		//delete
		{
			cout << "Delete Data : ";
			cin >> judul;

			deleteNode(judul);
			
		}
		if(choice == 3)   //display
		{

			cout << endl << endl;
			cout << "Data Anda: " << endl;
			cout << "Judul" << "\t" << "Pengarang" << "\t" << "Harga" << endl ;
			myPtr = headPtr;
			while (myPtr != NULL)
			{
					cout << "  " << myPtr->judul << "\t" ;
					cout << "    " << myPtr->pengarang << "\t" ;
					cout << "\t" << myPtr->harga  ;
					myPtr = myPtr->nextPtr;
					cout << endl;
			}
			cout << endl;
		}
		if(choice == 4)   //Exit
		{
			cout << "Thank You" << endl;
		}
	}
	
	
}

[anitaNg]

hey Jonsca, i think i figured it out already. thanks for helping me! :) i really appreciate it :)

[jonsca]

hey Jonsca, i think i figured it out already. thanks for helping me! :) i really appreciate it :)

No problem.

it seems to workout,thanks to you

By and large, you solved it on your own, so give yourself credit too! :)