Addressbook writing to file - c++

Question

I have an Addressbook C++ program that compiles and everything, but I cannot figure out how to write it to a file that saves the data each time it exits. Here is my code:
//AddressBook Program
#include <iostream>
#include <string.h>
#include <cstdlib>
#include <stdio.h>
using namespace std;
class AddressBook{
public :
AddressBook()
{
count = 0;
}
void AddEntry();
void DisplayAll();
void DisplayEntry(int i); // Displays one entry
void SearchEntry();
int MainMenu();
struct Entry_Struct
{
char firstName[ 15 ] ;
char lastName[ 15 ] ;
char birthday[ 15 ] ;
char phone[ 15 ] ;
char email[ 15 ] ;
};
Entry_Struct entries[100];
unsigned int count;
};
void AddressBook::AddEntry()
{
cout << "Entry number " << (count + 1) << " : " << endl;
cout << "Enter First Name: ";
cin >> entries[count].firstName;
cout << "Enter Last Name: ";
cin >> entries[count].lastName;
cout << "Enter Date of Birth: ";
cin >> entries[count].birthday;
cout << "Enter Phone Number: ";
cin >> entries[count].phone;
cout << "Enter Email: ";
cin >> entries[count].email;
++count; // tally total entry count
}
void AddressBook::DisplayEntry(int i)
{
cout << "Entry[" << i + 1 << "] : " << endl; // states # of entry
cout << "First name : " << entries[i].firstName << endl;
cout << "Last name : " << entries[i].lastName << endl;
cout << "Date of birth : " << entries[i].birthday << endl;
cout << "Phone number : " << entries[i].phone << endl;
cout << "Email: " << entries[i].email << endl;
}
void AddressBook::DisplayAll()
{
cout << "Number of entries : " << count << endl;
for(int i = 0;i < count;++i)
DisplayEntry(i);
}
void AddressBook::SearchEntry()
{
char lastname[32];
cout << "Enter last name : ";
cin >> lastname;
for(int i = 0;i < count;++i)
{
if(strcmp(lastname, entries[i].lastName) == 0)
{
cout << "Found ";
DisplayEntry(i);
cout << endl;
}
}
}
// Your class
AddressBook my_book;
int MainMenu()
{
int num;
bool bQuit = false;
// Put all your code into a while loop.
while(bQuit == false)
{
cout << "+-------------------------------------+" << endl;
cout << "| Address Book Menu |" << endl;
cout << "| |" << endl;
cout << "| 1- Add an entry |" << endl;
cout << "| 2- Search for an entry by last name |" << endl;
cout << "| 3- Display all entries |" << endl;
cout << "| 4- Exit |" << endl;
cout << "| |" << endl;
cout << "+-------------------------------------+" << endl;
cout << endl;
cout << "Please enter a number for one of the above options: ";
cin >> num;
cout << endl;
if (num == 1)
my_book.AddEntry();
else if (num == 2)
my_book.SearchEntry();
else if (num == 3)
my_book.DisplayAll();
else if (num == 4)
bQuit = true;
else
cout << "Invalid choice. Please try again" << endl;
cout << endl;
}
return 0;
}
int main (){
MainMenu();
return 0;
}
I've gone over my textbook all day and nothing I'm doing is working.

Answer 1

Here is a basic example of opening, and writing an output file,
// basic file operations
#include <iostream>
#include <fstream>
using namespace std;
int main () {
ofstream outfile;
outfile.open ("addressbook.txt");
outfile << "Daffy,Duck,123 Main Street,Anytown,OH,USA,123-456-7890\n";
myfile.close();
return 0;
}

Answer 2

You need to have an inserter for your class. It's done using operator <<:
// Inside your class:
friend std::istream& operator<<(std::ostream& os, const AddressBook ab)
{
return os << /* ... */
}
As you can see, a user-defined operator << can be implemented in terms of the pre-defined standard inserter. You can use it in the following way:
std::ifstream in("yourtxtfile.txt");
in << my_book;