(Online Address Book Revisited) Programming Exercise 9 in Chapter 3 could handle

Question

(Online Address Book Revisited)

Programming Exercise 9 in Chapter 3 could handle a maximum of only 500 entries.

Using linked lists, redo the program to handle as many entries as required.

Add the following operations to your program:

a. Add or delete a new entry to the address book.

b. When the program terminates, write the data in the address book to a disk.

This is the code I have so far, it runs but there are errors with how it runs.

// Ch5Ex1.cpp : Defines the entry point for the console application.

//

#include "stdafx.h"

#include <iostream>

#include <string>

#include <ctype.h>

using namespace std;

const int myMaxLength = 255;

struct myList

{

char myName[myMaxLength];

char myAddress[myMaxLength];

char myPhone[myMaxLength];

myList *myNext;

};

typedef myList myAddress;

void insertToList();

void removeFromList();

void displayName();

void listMyNames();

void freeMyList();

myList *myHead = NULL;

int main()

{

char myInput;

while (1)

{

cout << "Welcome to the Address book ";

cout << "Pick an option: ";

cout << "A. Add a person B.Delete a person C.Print D.List names E.Quit ";

cin >> myInput;

switch (toupper(myInput))

{

case 'A':

insertToList();

break;

case 'B':

removeFromList();

break;

case 'C':

displayName();

break;

case'D':

listMyNames();

break;

case 'E':

freeMyList();

return (0);

default:

cout << "Unknown command ";

}

}

}

void insertToList()

{

myAddress *mynewName = new myAddress;

cout << "Enter name ";

cin >> mynewName->myName;

cout << " Enter address ";

cin >> mynewName->myAddress;

cout << " Enter phone number ";

cin >> mynewName->myPhone;

mynewName->myNext = myHead;

myHead = mynewName;

}

void removeFromList()

{

myAddress *removePtr;

myAddress *previousPtr;

char delName[myMaxLength];

cout << "Enter name to delete: ";

cin >> delName[myMaxLength];

if (myHead == NULL)

{

cout << "No list to delete ";

return;

}

if (strcmp(myHead->myName, delName) == 0)

{

removePtr = myHead;

myHead = myHead->myNext;

delete removePtr;

return;

}

previousPtr = myHead;

while (previousPtr->myNext != NULL)

{

if (strcmp(previousPtr->myNext->myName, delName) == 0)

{

removePtr = previousPtr->myNext;

previousPtr->myNext = removePtr->myNext;

delete removePtr;

return;

}

previousPtr = previousPtr->myNext;

}

cout << " No Name found ";

}

void displayName()

{

char myName[myMaxLength];

myAddress *mysearchPtr;

cout << "Enter the name you want to look for: ";

cin >> myName[myMaxLength];

mysearchPtr = myHead;

while (mysearchPtr != NULL)

{

if (strcmp(mysearchPtr->myName, myName) == 0)

{

cout << "Address: " << mysearchPtr->myAddress << endl;

cout << "Telephone #: " << mysearchPtr->myPhone << endl;

return;

}

mysearchPtr = mysearchPtr->myNext;

}

cout << "No name found! ";

}

void listMyNames()

{

myAddress *mytempPtr;

cout << "All names in address book: " << endl;

mytempPtr = myHead;

while (mytempPtr != NULL)

{

cout << mytempPtr->myName << endl;

mytempPtr = mytempPtr->myNext;

}

}

void freeMyList()

{

myAddress *removePtr;

while (myHead != NULL)

{

removePtr = myHead;

myHead = myHead->myNext;

delete removePtr;

}

}

Explanation / Answer

// File Name: LinkedListAddress.cpp

#include <fstream>
#include <iostream>
#include <string.h>
#include <ctype.h>
using namespace std;
// Declares a constant for maximum length of the string
const int myMaxLength = 255;

// Creates a structure for address list
struct myList
{
// To store name
char myName[myMaxLength];
// To store address
char myAddress[myMaxLength];
// To store phone number
char myPhone[myMaxLength];
// To store pointer to next node
myList *myNext;
};// End of structure

// Renames myList to myAddress
typedef myList myAddress;

// Prototype of functions
void insertToList();
void removeFromList();
void displayName();
void listMyNames();
void freeMyList();
void writeList();
// Creates a head pointer and assigns it to null
myList *myHead = NULL;

// main function definition
int main()
{
// To store user choice
char myInput;
// Loops till user choice is not 'E'
while (1)
{
// Displays menu
cout << "Welcome to the Address book ";
cout << "Pick an option: ";
cout << "A. Add a person B.Delete a person C.Print D.List names E.Quit ";
// Accepts user choice
cin >> myInput;
// Checks user choice and calls appropriate function
switch (toupper(myInput))
{
case 'A':
// Calls the function to insert a node
insertToList();
break;
case 'B':
// Calls the function to delete a node
removeFromList();
break;
case 'C':
// Calls the function to display a node information
displayName();
break;
case'D':
// Calls the function to display all names
listMyNames();
break;
case 'E':
// Calls the function to write list
writeList();
// Calls the function to delete all the nodes
freeMyList();
return (0);
default:
cout << "Unknown command ";
}// End of switch case
}// End of while loop
}// End of main function

// Function to insert a node to list
void insertToList()
{
// Creates a new node
myAddress *mynewName = new myAddress();
// Accepts data
cout << "Enter name ";
cin >> mynewName->myName;
cout << " Enter address ";
cin >> mynewName->myAddress;
cout << " Enter phone number ";
cin >> mynewName->myPhone;
// new node next points to head
mynewName->myNext = myHead;
// new node address is assigned to head
myHead = mynewName;
}// End of function

void removeFromList()
{
// Creates two pointers to point of type myAddress
myAddress *removePtr;
myAddress *previousPtr;
// To store the name entered by the user
char delName[myMaxLength];
cout << "Enter name to delete: ";
// Accepts the name
cin >> delName[myMaxLength];
// Checks if the head is null list is empty
if (myHead == NULL)
{
cout << "No list to delete ";
return;
}// End of if condition
// Checks if the current node name is equals to name entered by the user
if (strcmp(myHead->myName, delName) == 0)
{
// head address is assigned to remove pointer
removePtr = myHead;
// move to next node
myHead = myHead->myNext;
// delete the node pointed by remove pointer
delete removePtr;
return;
}// End of if condition
// head addressed is assigned to previous pointer
previousPtr = myHead;
// Loops till previous pointer next is not null
while (previousPtr->myNext != NULL)
{
// Checks if the current node name is equals to name entered by the user
if (strcmp(previousPtr->myNext->myName, delName) == 0)
{
// previous pointer next address is assigned to remove pointer
removePtr = previousPtr->myNext;
// Move to next node
previousPtr->myNext = removePtr->myNext;
// delete the node pointed by remove pointer
delete removePtr;
return;
}// End of if condition
// Previous pointer is pointing to previous pointer next
previousPtr = previousPtr->myNext;
}// End of while loop
// Otherwise not found
cout << " No Name found ";
}// End of function

// Function to display node contents
void displayName()
{
// To store the name entered by the user
char myName[myMaxLength];
// Creates a temporary pointer
myAddress *mysearchPtr;
// Accepts a name from the user
cout << "Enter the name you want to look for: ";
cin >> myName[myMaxLength];
// temporary pointer points to head
mysearchPtr = myHead;
// Loops till temporary pointer is not null
while (mysearchPtr != NULL)
{
// Checks if the current node name is equals to name entered by the user
if (strcmp(mysearchPtr->myName, myName) == 0)
{
// Displays the address and telephone number of the searched node
cout << "Address: " << mysearchPtr->myAddress << endl;
cout << "Telephone #: " << mysearchPtr->myPhone << endl;
return;
}// End of if condition
// Temporary pointer points to next node
mysearchPtr = mysearchPtr->myNext;
}// End of while loop
cout << "No name found! ";
}// End of function

// Function to display names stored in all nodes
void listMyNames()
{
// Declares a temporary pointer
myAddress *mytempPtr;
cout << "All names in address book: " << endl;
// temporary pointer points to head
mytempPtr = myHead;
// Loops till temporary pointer is not null
while (mytempPtr != NULL)
{
// Displays the name stored in the current node
cout << mytempPtr->myName << endl;
// Move to next node
mytempPtr = mytempPtr->myNext;
}// End of while loop
}// End of function

// Function to delete all nodes
void freeMyList()
{
// Declares a temporary pointer
myAddress *removePtr;
// Loops till head is not equals to null
while (myHead != NULL)
{
// Stores the address of the head in temporary node
removePtr = myHead;
// Move next
myHead = myHead->myNext;
// Delete the temporary node
delete removePtr;
}// End of while loop
}// End of function

// Function to write all the nodes to the file
void writeList()
{
// Declares ofstream object
ofstream outFile;
// Opens the file for writing
outFile.open("address.txt");
// Creates a temporary pointer points to head
myAddress *mysearchPtr = myHead;
// Loops till temporary node is not equals to null
while (mysearchPtr != NULL)
{
// Write the record to file
outFile<<mysearchPtr->myName<<" "<<mysearchPtr->myAddress<<" "<<mysearchPtr->myPhone<<endl;
// Move to next
mysearchPtr = mysearchPtr->myNext;
}// End of while loop
}// End of function

Sample Output:

Welcome to the Address book
Pick an option:
A. Add a person
B.Delete a person
C.Print
D.List names
E.Quit
a
Enter name Pyari
Enter address BAM
Enter phone number 1233215566
Welcome to the Address book
Pick an option:
A. Add a person
B.Delete a person
C.Print
D.List names
E.Quit
a
Enter name Mohan
Enter address BBSR
Enter phone number 1112323561
Welcome to the Address book
Pick an option:
A. Add a person
B.Delete a person
C.Print
D.List names
E.Quit
a
Enter name Sahu
Enter address RKL
Enter phone number 1255545654
Welcome to the Address book
Pick an option:
A. Add a person
B.Delete a person
C.Print
D.List names
E.Quit
d
All names in address book:
Sahu
Mohan
Pyari
Welcome to the Address book
Pick an option:
A. Add a person
B.Delete a person
C.Print
D.List names
E.Quit
e

address.txt file contents

Sahu
RKL
1255545654
Mohan
BBSR
1112323561
Pyari
BAM
1233215566

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