Linked List AddressBook Help

[Jubberwacky]

Can anyone help me to fix one little problem i am having. When i change the name of an entry, the name changes but the ID number associated with the Entry Deletes. I want the program to leave the ID number alone and print it with the New name. Can anyone help me figure this out?

The Code that i have

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>

using namespace std;

char current;

class Person
{
public:
Person(string newName)
{
    name = newName;
    nextPerson = 0;
}

string name;
string IDNumb;
Person *nextPerson;
};


Person* pHeadNode;


void DrawMenu()
{
cout << "------------Menu-------------" << endl;
cout << "1. Enter a Person to the List" << endl;
cout << "2. Delete a Person from the List"  << endl;
cout << "3. Change a Person's name in the List" << endl;
cout << "4. Display Entries" << endl;
cout << "5. Locate Person by ID Number" << endl;
cout << "6. Locate Person by Name" << endl;
cout << "7. Load List from File" << endl;
cout << "8. Save List to the File" << endl;
cout << "9. Exit the program"  << endl;
cout << "" << endl;
cout << "You choice: ";
}

Person* FindName(string name)
{
if (pHeadNode)
{
    Person *pCurrentNode = pHeadNode;
    while(pCurrentNode && pCurrentNode->name!=name)
    {
        if (pCurrentNode->name==name)
            return pCurrentNode;

        pCurrentNode = pCurrentNode->nextPerson;
    }
}
return 0;
}



void InsertNewNode(Person* pNewNode)
{
  if (!pHeadNode || (pNewNode->name < pHeadNode->name))
{
    pNewNode->nextPerson = pHeadNode;
    pHeadNode = pNewNode;
} else {
    Person *pCurrentNode = pHeadNode;
    Person *pPrevNode = pCurrentNode;
    while(pCurrentNode && pCurrentNode->name < pNewNode->name)
    {
        pPrevNode = pCurrentNode;
        pCurrentNode = pCurrentNode->nextPerson;
    }
    pNewNode->nextPerson = pPrevNode->nextPerson;
    pPrevNode->nextPerson = pNewNode;
}
}

void AddNewEntry()
{
string name;
string IDNumb;
cout << "Enter name of new Entry: ";
getline(cin, name);
cin.clear();
cin.sync();

getline(cin, name);

if (pHeadNode)
{
    if (FindName(name))
    {
        cout << "" << endl;
        cout << "Name already exists";
        cout << "" << endl;
        return;
    }
}

cout << "Enter ID Number for new Entry: ";
getline(cin, IDNumb);



if (pHeadNode)
{
    Person* pNewNode = new Person(name);
    pNewNode->IDNumb = IDNumb;

    InsertNewNode(pNewNode);
} else {
    pHeadNode = new Person(name);
    pHeadNode->IDNumb = IDNumb;

}

cout << "" << endl;
cout << "New Entry is added" << endl;
cout << "" << endl;
}

void DeleteEntry()
{
string name;

if (pHeadNode)
{
    cin.clear();
    cin.sync();

    cout << "Enter name of Entry you want to delete: ";
    getline(cin, name);

    Person *pCurrentNode = pHeadNode;
    Person *pPrevNode = pCurrentNode;
    while(pCurrentNode && pCurrentNode->name!=name)
    {
        if (pCurrentNode->name==name)
            break;

        pCurrentNode = pCurrentNode->nextPerson;
    }

    if (pCurrentNode)
    {
        if (pCurrentNode==pHeadNode)
        {
            pHeadNode = pCurrentNode->nextPerson;
        } else {
            pPrevNode->nextPerson = pCurrentNode->nextPerson;
        }
        delete pCurrentNode;
    } else {
        cout << "" << endl;
        cout << "Entry is not found" << endl;
        cout << "" << endl;
    }
} else {
    cout << "" << endl;
    cout << "Address book is empty already" << endl;
    cout << "" << endl;
    return;
}
}

void ChangeEntry()
{
string name;
string IDNumb;

if (pHeadNode)
{
    cin.clear();
    cin.sync();

    cout << "Enter name of Entry you want to edit: ";
    getline(cin, name);

    Person *pCurrentNode = pHeadNode;
    Person *pPrevNode = pCurrentNode;
    while(pCurrentNode && pCurrentNode->name!=name)
    {
        if (pCurrentNode->name==name)
            break;

        pCurrentNode = pCurrentNode->nextPerson;
    }

    if (pCurrentNode)
    {
        cin.clear();
        cin.sync();
        cout << "Enter name of new Entry: ";
        getline(cin, name);

        if (pHeadNode)
        {
            if (FindName(name))
            {
                cout << "" << endl;
                cout << "Name already exists";
                cout << "" << endl;
                return;
            }
        }

        if (pCurrentNode==pHeadNode)
        {
            pHeadNode = pCurrentNode->nextPerson;
        } else {
            pPrevNode->nextPerson = pCurrentNode->nextPerson;
        }
        delete pCurrentNode;


        cout << "" << endl;
        cout << "Entry is changed" << endl;
        cout << "" << endl;
    } else {
        cout << "" << endl;
        cout << "Entry is not found" << endl;
        cout << "" << endl;
    }
} else {
    cout << "" << endl;
    cout << "Address book is empty " << endl;
    cout << "" << endl;
    return;
}
}

void DisplayEntries()
{
    string getcontent;
    ifstream openfile ("PROG05.txt");
    if(openfile.is_open())
    {
        while(! openfile.eof())
        {
            getline(openfile, getcontent);
            cout << getcontent << endl;
        }
    }
}

void SearchEntriesName()
{
string name;
string IDNumb;

if (pHeadNode)
{
    cin.clear();
    cin.sync();

    cout << "Enter name of Entry you want to Search: ";
    getline(cin, name);

    Person *pCurrentNode = pHeadNode;
    Person *pPrevNode = pCurrentNode;
    while(pCurrentNode && pCurrentNode->name!=name)
    {
        if (pCurrentNode->name==name)
            break;

        pCurrentNode = pCurrentNode->nextPerson;
    }

    cout << pCurrentNode->name << endl;
    cout << pCurrentNode->IDNumb << endl;

}
}

void SearchEntriesIDNumb()
{
string name;
string IDNumb;

if (pHeadNode)
{
    cin.clear();
    cin.sync();

    cout << "Enter the ID Number of the entry you want to search: ";
    getline(cin, IDNumb);

    Person *pCurrentNode = pHeadNode;
    Person *pPrevNode = pCurrentNode;
    while(pCurrentNode && pCurrentNode->IDNumb!=IDNumb)
    {
        if (pCurrentNode->IDNumb==IDNumb)
            break;

        pCurrentNode = pCurrentNode->nextPerson;
    }

    cout << pCurrentNode->name << endl;
    cout << pCurrentNode->IDNumb << endl;

}
}


void SaveListToFile()
{
ofstream outfile;

outfile.open("PROG05.txt");

Person* pCurrentNode = pHeadNode;
while(pCurrentNode)
{
    Person* pNode = pCurrentNode;
    pCurrentNode = pCurrentNode->nextPerson;
    outfile << pNode->name << endl;
    outfile << pNode->IDNumb << endl;
}

outfile.close();
}

void LoadListFromFile()
{
ifstream infile;

infile.open("PROG05.txt");

string name;

while (getline(infile, name))
{
    string IDNumb;
    getline(infile, IDNumb);

    if (!pHeadNode)
    {
        pHeadNode = new Person(name);
        pHeadNode->IDNumb = IDNumb;

    } else {
        Person *pCurrentNode = pHeadNode;
        Person *pPrevNode = pCurrentNode;
        while(pCurrentNode)
        {
            pPrevNode = pCurrentNode;
            pCurrentNode = pCurrentNode->nextPerson;
        }
        pPrevNode->nextPerson = new Person(name);
        pPrevNode->nextPerson->IDNumb = IDNumb;

    }

}


infile.close();
}

int main()
{
int choice;
bool stop = false;

LoadListFromFile();
do
{
    do
    {
        DrawMenu();
        cin >> choice;
        if (choice<1 || choice>9)
            cout << "Incorrect choice. Try again" << endl << endl;
    }while(choice<1 || choice>9);

    switch(choice)
    {
        case 1:
            AddNewEntry();
            SaveListToFile();
            break;
        case 2:
            DeleteEntry();
            SaveListToFile();
            break;
        case 3:
            ChangeEntry();
            SaveListToFile();
            break;
        case 4:
            DisplayEntries();
            break;
        case 5:
            SearchEntriesIDNumb();
            break;
        case 6:
            SearchEntriesName();
            break;
        case 7:
            LoadListFromFile();
            DisplayEntries();
            cout << "List has been Loaded" << endl;
            break;
        case 8:
            SaveListToFile();
            cout << "List has been Saved to the File" << endl;
            break;
        case 9:
            cout << "Thank you for using the program" << endl;
            stop = true;
            break;
        default:

            break;
    }

}while(!stop);
SaveListToFile();

Person* pCurrentNode = pHeadNode;
while(pCurrentNode)
{
    Person* pNode = pCurrentNode;
    pCurrentNode = pCurrentNode->nextPerson;
    delete pNode;
}

return 0;
}

[Jubberwacky]

The code is Deleting the Name also and not replacing it. I need the function to Change the Name and keep the ID Number.

[doug4]

In lines 210-216 you delete the found node instead of changing it.

[Jubberwacky]

So would I just need to delete the code on those lines? Or do I need to change the code?

[doug4]

Think about it for a minute. You have created a linked list with elements in alphabetical order according to the name field. Now you are taking a node and changing the name field. What needs to happen to this structure you just located?

I was going to leave this as an open-ended question, but decided to give you the answer.
1. You need to replace the contents of the name field with the new name.
2. The list element is (probably) no longer in alphabetical order, so it must be removed from the list.
3. The modified element must be re-inserted into the list in the correct location.

Make sure the updated node has the old ID value and the new name. Then you're good.

[Jubberwacky]

I have the code to where the program is Changing the name and not deleting it. But how am i supposed to get the ID Number to not delete and to print with the changed name?

[Jubberwacky]

void ChangeEntry()
{
string name;
string IDNumb;

if (pHeadNode)
{
    cin.clear();
    cin.sync();

    cout << "\nEnter name of Entry you want to edit: ";
    getline(cin, name);

    Person *pCurrentNode = pHeadNode;
    Person *pPrevNode = pCurrentNode;
    while(pCurrentNode && pCurrentNode->name!=name)
    {
        if (pCurrentNode->name==name)
            break;

        pCurrentNode = pCurrentNode->nextPerson;
    }

    if (pCurrentNode)
    {
        cin.clear();
        cin.sync();
        cout << "\nEnter name of new Entry: ";
        getline(cin, name);

        if (pHeadNode)
        {
            if (FindName(name))
            {
                cout << "" << endl;
                cout << "Name already exists";
                cout << "" << endl;
                return;
            }
        }

        if (pCurrentNode==pHeadNode)
        {
            pHeadNode = pCurrentNode->nextPerson;
        } else {
            pPrevNode->nextPerson = pCurrentNode->nextPerson;
        }
        delete pCurrentNode;

        cout << "\nEnter ID Number for new Entry: ";
        getline(cin, IDNumb);

        Person* pNewNode = new Person(name);
        pNewNode->IDNumb = IDNumb;
        InsertNewNode(pNewNode);

        cout << "" << endl;
        cout << "Entry is changed" << endl;
        cout << "" << endl;
    } else {
        cout << "" << endl;
        cout << "Entry is not found" << endl;
        cout << "" << endl;
    }
} else {
    cout << "" << endl;
    cout << "Address book is empty " << endl;
    cout << "" << endl;
    return;
}
}

This is what i have now for the change entry function. It changes the name and the Id number. How would i go about just leaving the ID Number alone?

[doug4]

First I refer back to my original steps:

1. You need to replace the contents of the name field with the new name.
2. The list element is (probably) no longer in alphabetical order, so it must be removed from the list.
3. The modified element must be re-inserted into the list in the correct location.

Then your question:

But how am i supposed to get the ID Number to not delete and to print with the changed name?

Then look at your code, esp. lines 48-55.

Notice, I never said to delete the node. I said to remove it from and reinsert it into the list. However, you are going to the effort of deleting it and creating a new node. And on top of it, you ask the user for a new ID number.

You need to do 1 of 2 things:
1. (perferred) don't delete the old node. Replace lines 48 - 55 with

pCurrentNode->name = name;
InsertNewNode(pCurrentNode);

2. Save the ID number from pCurrentNode sometime before line 48, get rid of lines 50 - 51, and insert the saved ID number into the new node in line 54.