C/C++ :: File I/O And Removing Duplicates

I have a program that's supposed to read in a file with comma seperated values. This file contains duplicates. The goal is to write a new file that does not contain any of the duplicates. I've successfully written the code to read in a file and create a new, identical file, but I'm failing at deleting the duplicates.

The format of each line in the file is: index,first_name,last_name,address,city,state,zip_code

Example: 1,John,Savage,579 Lone Street,Providence,RI,02903

As a requirement for the assignment, I've defined a Person class:

//File: Person.h
struct Person {
string index;
string first_name;
string last_name;

[Code] .....

This code writes the file I want (overlooking the duplicates) if I implement my equality operator as follows:

bool operator ==(const Person &a, const Person &B)/>
{
return false; //placeholder
}

Obviously this doesn't get the job done, since it will never detect a duplicate. The problem is that whenever I try to write any meaningful code, the program writes an empty file. The idea I've been trying to implement is to compare each of the members of Person like this:

bool operator ==(const Person &a, const Person &B)/>
{
//if two Person objects have equivalent names, they are duplicates
return ( (a.first_name == b.first_name) && (a.last_name == b.last_name) )
}

At first I thought the program was working just as before, but then deleting each line of the file as the result of an error in my code. However, I tried troubleshooting the problem by adding in

cout << a.last_name;

to parts of my code so I could see the value in certain places. Whenever I add this line or try to access a member of Person, the program writes a blank file.