Writing user data to a file - c++

Question

I am trying to create a program that ask for sales amount and displays total salary and writes the entry to a file. However my program has is only writing the last entry to the file. I have searched online for 2hours for a solution and cant find one.
I want all of the input to write to my file not just the last one
#include <fstream>
#include <iostream>
#include <iomanip>
using namespace std;
void SavingFile(); //Declartion
void Calculate();
char FileName[20];
double GrossPay;
double TotalSalary;
int employeeID=0;
char response;
int i=1;
int main()
{
SavingFile();
}
void SavingFile()
{
cout << "\nEnter the name of the file you want to create: ";
cin >> FileName;
do
{
employeeID++;
cout << endl << endl << "Enter sales amount for sales person ID " << employeeID <<" : $";
cin >> GrossPay;
Calculate();
cout <<"Sales amount for ID " << employeeID <<" : $" << TotalSalary <<endl;
cout <<endl <<endl;
do
{
ofstream Employee(FileName);
Employee <<"Employee ID: "<< employeeID <<" Sales Amount: $" << TotalSalary <<endl;
cout << endl;
i++;
}
while
(employeeID == i);
cout << "Do you want to process another employee ? (y/n): ";
cin >> response;
}
while ( (response == 'Y') || (response == 'y') );
}
void Calculate() // definition
{
TotalSalary = (GrossPay * .10) + 150;
//return TotalSalary;
}

Answer 1

You are overwriting the file every time you write to it.
If you want to append to the file, you need to open the file using the ios_base::app flag in addition to ios_base::out.
In your code, you must replace this:
ofstream Employee(FileName);
with this:
ofstream Employee(FileName, ios_base::out | ios_base::app);
To learn more, you can read this page on the constructor of the ofstream class. Among other things, you will find a description of the various flags you can use and what they mean.

Answer 2

I won't rewrite your code for you, but I'll explain the logic that you need to rewrite.
In a loop, you read a value, and call Calculate, which sets a global variable called TotalSalary. The cout probably looks ok. Try adding a cout into the while loop where you are outputting the file, and you'll see that the values aren't what they used to be.
The problem is that every time you call Calculate, you overwrite TotalSalary. You're not saving these values anywhere, but by looping through, you're assuming that the values are still there.
The solution is to write to the output file at the same time as you write to your cout. Open the ofstream at the top of main, and just output to there like you are outputting to cout.
There's no need to open the file each time in a loop, and in fact you shouldn't. (Though appending would help, if that's what you should have been doing.)