Code Sample #7

//               Course:  CS2400-60 Computer Science 2
//                 Name:  Abdalkarim, Marina
//           Assignment:  Programming Assignment P8.1
//               Remark:  The program tests all functions.
#include <iostream>
#include <string>
#include <iomanip>
#include <cassert>
using namespace std;
class savingsAcct
{
friend istream& operator>>(istream&, savingsAcct&);
// Postcondition: the integer values entered by the user are assigned to the data members
friend ostream& operator<<(ostream&, const savingsAcct&);
// Postcondition: displays the contents of the class passed to the function
public:
savingsAcct();
// Postcondition: balance is set to 0
savingsAcct(string acctNum, double amt);
// Postcondition: balance is set to the value passed to parameter amt
static double * getAddressOfVar_annulRate();
// Postcondition: return the address of static variable annualRate (should the same for all objects!)
static double getAnnualRate();
// Postcondition: returns annual interest rate
static void setAnnualRate(double rate);  	// change the annual interest rate
// Postcondition: annualRate has been changed to the value passed to parameter rate
void computeIntrest();
// Interest is computed at the end of each month using monthly interest rate (i.e.,annualRate/12)
// Postcondition: interest is computed at the end of the month using the current balance
private:
string acctNo;      	            // e.g., A1234
double balance;
static double annualRate;  	    // classwide; store in a memory location shared by objects 
double interest;    	            // monthly interest
};
double savingsAcct::annualRate;
int main()
{
	cout << "As of now, no object has been declared.\n";
	cout << "However, static data members exist before any object is declared:" << endl;
	cout << "   The address of its storage location: " << int(savingsAcct::getAddressOfVar_annulRate()) << endl;
	cout << "                  Annual interest rate: " << savingsAcct::getAnnualRate() * 100 << "%" << endl << endl;
	cout << "Still no object has declared, we now set the interest rate to 1.5%." << endl;
	savingsAcct::setAnnualRate(0.015);
	cout << "    Now, the annual interest rate is: " << savingsAcct::getAnnualRate() * 100 << "%" << endl << endl;
	cout << "We now declare and initialize 2 savingAcct objects." << endl;
	cout << "We also compute interest at the end of 1st month and display their contents:\n\n";
	savingsAcct s1("A1234", 5000), s2("A9876", 8000);
	s1.computeIntrest();
	s2.computeIntrest();
	cout << s1 << endl << endl;
	cout << s2 << endl << endl;
	cout << "We now display the address of static variable annualRate" << endl;
	cout << "   by calling \"getAddressOfVar_annulRate()\" member function" << endl << endl;
	cout << "Via s1: the address of \"annualRate\" is  " << int(s1.getAddressOfVar_annulRate()) << endl;
	cout << "Via s2: the address of \"annualRate\" is  " << int(s2.getAddressOfVar_annulRate()) << endl;
	cout << "Via s1: the address of \"annualRate\" is  " << int(savingsAcct::getAddressOfVar_annulRate()) << endl;
	cout << "\nIt should be quite clear that static members are indeed \"class-wide!!!\"" << endl;
	cout << "Note: calling a static member function, \"this\" pointer is not involved!!!\n\n";
    return 0;
}
savingsAcct::savingsAcct()
{
	acctNo = "Nothing";
	balance = 0;
	savingsAcct::annualRate = 0;
	interest = 0;
}
savingsAcct::savingsAcct(string acctNum, double amt)
{
	acctNo = acctNum;
	balance = amt;
}
istream& operator>>(istream& in, savingsAcct &x)
{
	in >> x.acctNo >> x.balance;
	return in;
}
ostream& operator<<(ostream& out, const savingsAcct &x)
{
	cout << fixed << setprecision(2);
	out << "Account No: " << x.acctNo << endl;
	out << "   Balance: $ " << x.balance << endl;
	out << "  Interest: $ " << setw(7) << x.interest << endl;
	return out;
}
double *savingsAcct::getAddressOfVar_annulRate()
{
	double *address;
	address = &(savingsAcct::annualRate);
	return address;
}
double savingsAcct::getAnnualRate()
{
	return savingsAcct::annualRate;
}
void savingsAcct::setAnnualRate(double rate)
{
	savingsAcct::annualRate = rate;
}
void savingsAcct::computeIntrest()
{
	interest = (balance * (1 + (savingsAcct::annualRate * 0.0833))) - balance;
}