How do I add data from my program to a file for future use?

[steinzfan]

Here is my code, I want to be able to store customers, their data, etc and be able to view that data again and add to it the next time I run the program.

#include <iostream>

using namespace std;
//include protype functions
enum AccountType 
{unknown = -1, Checking, Savings, CreditCard, InstantAccess};

struct customerInfo 
	{
		char firstName[20]; 
		char lastName[20];
		float amount;
		AccountType type;
	};

int main()
{
	char choice;
	bool terminate = false;
	int i = 0;
	const int SIZE = 100;

	customerInfo myAccount[SIZE];

	//float depositAmount (){};
	//float withdrawAmount (){};

	while (!terminate)
	{
		cout << "WELCOME TO SO-AND-SO BANK!\n\n" << "Please enter an option, are you a:\n\n" 
		<< "A)Customer\n" 
		<< "B)Bank Employee\n" 
		<< "C)Bank Supervisor\n" 
		<< "D)Quit the application\n\n";
		cin >> choice;

		switch(choice)
		{
		case 'a':
		case 'A':
		cout << "Welcome to So-and-So Bank Customer Services!\n" << "Please enter an option:\n\n";
		//Customer options
		cout << "A)Functions: Balance Inquiry\n" 
		<< "B)Deposit Funds\n" 
		<< "C)Withdraw funds\n"
		<< "D)Transfer Funds to another account (like from Checking to Savings or to Credit Card)\n"
		<< "E)Anything else that you want to add\n" 
		<< "F)Quit the application\n\n";
		cin >> choice;

		switch(choice)
		{
		case 'a':
		case 'A':
			//struct name, amount, type
			for(i = 0; i < SIZE; i++) //edit
			{
				cout << "Enter your first name (20 characters or less):\n\n";
				cin >> myAccount[i].firstName;
				cout << "Enter your last name (20 characters or less):\n\n";
				cin >> myAccount[i].lastName;

				loop:
				cout << "What type of account do you wish to view?\n\n"
					<< "1. Checking\n" << "2. Savings\n"  << "3. CreditCard\n" 
					<< "4. InstantAccess\n" << "5. Quit";
				cin >> choice; //consider
			{
				if(choice == '1')
				{
					myAccount[i].type = Checking;
				}
				if(choice == '2')
				{
					myAccount[i].type = Savings;
				}
				if(choice == '3')
				{
					myAccount[i].type = CreditCard;
				}
				if(choice == '4')
				{
					myAccount[i].type = InstantAccess;
				}
				if(choice == '5')
				{
					cout << "You have chosen to quit, we appreciate your business.";
					terminate = true;
				}
				else
				{
					cout << "You've entered an invalid option, please try again";
					goto loop;
				}
			}

				//include breakable
				cout << "Your account balance is: " << myAccount[i].amount;
				//
			};

			break;
		case 'b':
		case 'B':
			//depositAmount();
			break;
		case 'c':
		case 'C':
			//withdrawAmount();
			break;
		case 'd':
		case 'D':
			//transfer enum
			break;
		case 'e':
		case 'E':
			//while or goto loop
			break;
		case 'f':
		case 'F':
		cout << "You have chosen to quit, we appreciate your business.";
		terminate = true;
			break;
		default:
		cout << "You have entered an invalid option, please try again.\n\n";
			break;
		}
		break;

		case 'b':
		case 'B':
		cout << "Welcome to So-and-So Bank Employee Services!\n" << "Please enter an option:\n\n";
		//Cascading customer data
		//a.Everything in the Customer Interface, plus
		cout << "A)Interface to ADD a new Customer to the Bank\n"
		<< "B)Interface to DELETE a  Customer from the Bank\n"
		<< "C)Search for a Record based on a “Name of a Customer” (using simple Sequential Search)\n"
		<< "D)Quit the application\n\n";
		cin >> choice;

		switch(choice)
		{
		case 'a':
		case 'A':
			//struct new customer
			for(i = 0; i < SIZE; i++) //edit
			{
				cout << "Enter your first name (20 characters or less):\n\n";
				cin >> myAccount[i].firstName;
				cout << "Enter your last name (20 characters or less):\n\n";
				cin >> myAccount[i].lastName;
			};
			break;
		case 'b':
		case 'B':
			//struct delete customer (Case C w/ remove name)
			break;
		case 'c':
		case 'C':
			//for loop name search, cin i, i customer
			cout << "So-and-So Bank Customers:\n";
			for(i = 0; i < SIZE; i++)
			{
				cout << i << ". " << myAccount[i].lastName << ", " << myAccount[i].firstName << "\n";
			};
			cout << "Select customer number:\n\n";
			cin >> i;

			//cout << myAccount[i].amount;
			
			break;
		case 'd':
		case 'D':
		cout << "You have chosen to quit, we appreciate your business.";
		terminate = true;
			break;
		default:
		cout << "You have entered an invalid option, please try again.\n\n";
			break;
		}
		break;

		case 'c':
		case 'C':
		cout << "Welcome to So-and-So Bank Supervising Services!\n" << "Please enter an option:\n\n";
		//Cascading banker and customer data
		//a.Everything in Bank Teller Interface, plus
		cout << "A)Ability to List Total Number of Customers in Bank\n"
		<< "B)Ability to List Total Amount of Money in the Bank\n"
		<< "C)Ability to List Total Deposits in a Day\n"
		<< "D)Ability to List Total Withdrawals in a Day\n"
		<< "E)Ability to see/query detailed LOG of all transactions\n"
		<< "F)Quit the application\n\n";
		cin >> choice;

		switch(choice)
		{
		case 'a':
		case 'A':
			//for loop count customers
			break;
		case 'b':
		case 'B':
			//for loop count money 
			break;
		case 'c':
		case 'C':
			//for loop count deposits (amount?)
			break;
		case 'd':
		case 'D':
			//for loop count withdrawals (amount?)
			break;
		case 'e':
		case 'E':
			//enum results from b,c, and d. for loop allow search
			break;
		case 'f':
		case 'F':
		cout << "You have chosen to quit, we appreciate your business.";
		terminate = true;
			break;
		default:
		cout << "You have entered an invalid option, please try again.\n\n";
			break;
		}
		break;

		case 'd':
		case 'D':
		cout << "You have chosen to quit, we appreciate your business.";
		terminate = true;
		break;

		default:
		cout << "You have entered an invalid option, please try again.\n\n";
		break;
		}

	}
return 0;
}

[Cojones]

you can use something like

ofstream fout; // you declare an instance of the ofstream class 

fout.open("your file name"); //this opens your file 

int x=4;

fout << x; // you add 4 in your txt file
 
fout.close();  // when you finish you should call this method. 

For reading from a file you use

ifstream fin; 

int x;

fin.open("the same file as above");

fin >> x; // now x == 4; :) considering the example above

fin.close();

You need to #include "fstream"

[steinzfan]

And do I need to do this every time I declare or assign values to variables throughout the program?

[Duthomhas]

Yes. Except for an int x, you should be writing and reading customerInfo data to/from file.

One simple way to do it would simply to write each field of the customerInfo to its own line --meaning that every four lines would be for a single customer. You might even want to add a blank line between customers, just to make the file more human-readable.

John
Jones
12.80
checking

Mary
Smith
4279.15
savings

etc.

Now, all you need to do is write some functions to read and write a customerInfo structure. Since you are using C++, you can overload the << and >> stream operators:

ostream& operator << ( ostream& outs, const customerInfo& ci )
  {
  outs << ci.firstName << endl;
  ...  // Fill in the rest here
  return outs;
  }

istream& operator >> ( istream& ins, customerInfo& ci )
  {
  ins.getline( ci.firstName, sizeof( ci.firstName ) );
  ... // Fill in the rest here
  return ins;
  }

After that, you can load the entire file into a std::deque (or std::vector, or std::list, etc), make changes, then write the entire thing back out to file.

Hope this helps.

[steinzfan]

I'm a little vague about overloading, why do I do this?

[Duthomhas]

If you are unsure, write functions to do it instead.

void write_customerInfo( ostream& outs, const customerInfo& ci );
void read_customerInfo( istream& ins, customerInfo& ci );

Overloading is so you can do stuff like:

deque <customerInfo> customers;

customerInfo customer;
myfile >> customer;  // here's the overloaded extraction (input) operator
customers.push_back( customer );

instead of:

deque <customerInfo> customers;

customerInfo customer;
read_customerInfo( myfile, customer );
customers.push_back( customer );

Hope this helps.