Bank Program - Validing a PIN #

[kacebug]

I'm working on a bank account program and I need some help with the part that validates the PIN #. I know it will be a FOR statement of some sort, but could use a little help figuring out how to set this up. I need a variable, something to set it equal to and what else??? Here's my code - I got it running pretty well so far (just a few bugs I need to go back and fix) but there's nothing about validating a PIN yet...I'll want to put it in the int getPin part, right?

insert

//Final Project 

#include <iostream>
#include <cstdlib>
#include <string>
#include <fstream>

using namespace std;

class userAccount
{
private:
	string userName;
	int pin;
	string firstName;
	string lastName;
	int account;
	double balance;

public:
	
	userAccount()
	{
		//don't initialize because no parameters have been passed
	}
	
	userAccount(string u, string f, string l, int a, int p, double b)
	{
		userName=u;
		pin=p;
		firstName=f;
		lastName=l;
		balance=b;
		account=a;
	}

	string getUser()
	{
		return userName;
	}
	
	int getPin()
	{
		return pin;
	}

	int getAccount()
	{
		return account;
	}	
	string getFirstName()
	{
		return firstName;
	}

	string getLastName()
	{
		return lastName;
	}

	double getBalance()
	{
		return balance;
	}

	void printBalance()
	{
		cout<<"Your current balance is $ "<<balance<<endl;
	}

	void setPin()
	{
		cout<<"Enter your new PIN:  "<<endl;
		cin>>pin;
	}

	void printData()
	{
		cout<<"Enter Username:  "<<endl;
		cin>>userName;
		cout<<"Enter PIN "<<endl;
		cin>>pin;
		cout<<"Enter First Name: "<<endl;
		cin>>firstName;
		cout<<"Enter Last Name; "<<endl;
		cin>>lastName;
		cout<<"Enter Account Number: "<<endl;
		cin>>account;
		cout<<"Your current balance is $ "<<endl;
		cin>>balance;
	}

	void addDeposit()
	{
		double deposit;

		cout<<"Enter your deposit amount: $ "<<endl;
		cin>>deposit;
		balance = balance + deposit;
		cout<<"Your new balance is $ "<<balance;
		

	}
    void getWithdrawal()
    {
		double withdrawal;
		
	cout<<"Enter your withdrawal amount:  $ "<<endl;
    cin>>withdrawal;

	while(withdrawal > balance || withdrawal < 0)
	{
		cout<<"DENIED!  You have entered an inadequate amount."<<endl;
		cout<<"Please enter your withdrawal amount:  $ "<<endl;
		cin>>withdrawal;
    }

	balance = balance - withdrawal;
	cout<<"Your updated balance is now $ "<<balance;

}
};

int makeChoice()
{
	int choice;

	cout<<"1.)  View Account Info"<<endl;
	cout<<"2.)  Withdraw"<<endl;
	cout<<"3.)  Deposit"<<endl;
	cout<<"4.)  Change PIN"<<endl;
	cout<<"5.)  Quit"<<endl;
	cout<<"What action do you want to take?"<<endl;
	cin>>choice;
	return choice;

	}

	int main()
{
	//set up for reading from file
	ifstream accountData;
	accountData.open("Account.txt");


	string tempUserName;
	string tempFirstName;
	string tempLastName;
	int tempAccount;
	int tempPin;
	double tempBalance;
	int choice;
	int i;
	int totalUsers = 0; //keeps track of how many items we have total
	int activeUser = 0;
	int activePin = 0; //this is the item we are looking for and will modify
	userAccount users[100]; //all of our items are kept in this array

	//getting data from file into array
	while (!accountData.eof())
	{
		//get input from file
		accountData>>tempUserName>>tempAccount>>tempPin>>tempFirstName>>tempLastName>>tempBalance;
		//use constructor to create a temp object
		//cout<<tempUserName<<endl;
		userAccount tempUser(tempUserName, tempFirstName, tempLastName, tempAccount, tempPin, tempBalance);
		//assign temp object to a spot in our array
		users[totalUsers] = tempUser;
		//increment count for the next item
		totalUsers++;
	}
	
	//ask user for ID loop
	do
	{

		cout<<"Enter your user name: "<<endl;
		cin>>tempUserName;
		cout<<"Enter your PIN:  "<<endl;
		cin>>tempPin;
		activeUser = 0;

	
		//keeps look through array to find our item
		while(tempPin != users[activeUser].getPin() && tempUserName != users[activeUser].getUser())
		
		{
			activeUser++;
     	}
	
	}
	while(activeUser == totalUsers);
	{
	cout<<"Thank You for Visiting Bank 203"<<endl;
	users[activeUser].printBalance();
	choice = makeChoice();
	}
	while (choice != 5)
	{
		if (choice ==1)
		{
			users[activeUser].printData();
		}
		else if (choice == 2)
		{
			users[activeUser].getWithdrawal();
		}
		else if (choice == 3)
		{
			users[activeUser].addDeposit();
		}
		else if (choice == 4)
		{
			users[activeUser].setPin();
		}
		choice = makeChoice();
	}

	ofstream accountData2;
	accountData2.open("Account.txt");

	for ( i =0; i < totalUsers; i++)
	{
		accountData2<<users[i].getUser()<<users[i].getFirstName()<<users[i].getLastName()<<users[i].getAccount()<<users[i].getPin()<<users[i].getBalance()<<endl;
	}
	
	system("pause");
    return 0;
}

[rodrigorules]

something like this?

string pin;
cin >> pin;
bool is_valid = true;
for(int i=0;i<pin.length();++i)
{
   if( !isdigit(pin[i]) )
   {
      is_valid = false;
      break; 
   }
}

if(is_valid && pin.length() == 4)
   { // pin is valid  }