Compound Interest

Practical Learning: Starting the Exercise

1. Start Microsoft Visual C++
2. Create a new project named CompoundInterest1
3. Create the project as a Dialog Based and set the Dialog Title as Compound Interest
4. While still using the wizard:
   Change the application's Class Name to CExerciseApp
   Change the dialog's Class Name to CExerciseDlg
   Change the dialog's header file to ExerciseDlg.h
   Change the dialog's source file to ExerciseDlg.cpp
5. Delete the TODO line and the OK button. Change the Caption of the Cancel button to Close
6. Design the dialog box as follows:
    

   Control ID Caption Additional Properties Group Box   Values   Static Text   Principal: ...............   Edit Box IDC_PRINCIPAL   Align Text: Right Static Text   Interest: ...............   Edit Box IDC_ANNUAL_RATE   Align Text: Right Static Text   Number of Periods   Edit Box IDC_NUMBER_OF_PERIODS   Align Text: Center Group Box   Compound Frequency   Radio Button IDC_COMPOUND Monthly Group: True Left Text: True Radio Button   Quarterly Left Text: True Radio Button   Semiannually Left Text: True Radio Button   Annually Left Text: True Group Box       Static Text   Interest Earned   Edit Box IDC_INTEREST_EARNED   Align Text: Right Static Text   Amount Earned   Edit Box IDC_AMOUNT_EARNED   Align Text: Right Button IDC_CALCULATE_BTN C&alculate Default Button: True

7. Using either the ClassWizard or the Add Member Variable Wizard, add the following member variables to the controls:
    

   Identifier	Type	Value Variable
   IDC_AMOUNT_EARNED	CString	m_AmountEarned
   IDC_ANNUAL_RATE	CString	m_AnnualRate
   IDC_COMPOUND	int	m_Compound
   IDC_INTEREST_EARNED	CString	m_InterestEarned
   IDC_NUMBER_OF_PERIODS	CString	m_InterestEarned
   IDC_PRINCIPAL	CString	m_Principal

8. Initialize controls in the constructor of the dialog as follows:
    

   CExerciseDlg::CExerciseDlg(CWnd* pParent /*=NULL*/) : CDialog(CExerciseDlg::IDD, pParent) { //{{AFX_DATA_INIT(CExerciseDlg) m_Principal = _T("0.00"); m_AnnualRate = _T("0"); m_NumberOfPeriods = _T("1"); m_Compound = 3; m_InterestEarned = _T("0.00"); m_AmountEarned = _T("0.00"); //}}AFX_DATA_INIT m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME); }

9. Initiate the BN_CLICKED message of the Calculate button and implement its OnClick() event as follows:
    

   void CExerciseDlg::OnCalculateBtn() { // TODO: Add your control notification handler code here UpdateData(); double Principal, AnnualRate, InterestEarned; double FutureValue, RatePerPeriod; int NumberOfPeriods, CompoundType; Principal = atof(m_Principal); AnnualRate = atof(m_AnnualRate) / 100; switch( m_Compound ) { case 0: CompoundType = 12; break; case 1: CompoundType = 4; break; case 2: CompoundType = 2; break; case 3: CompoundType = 1; break; } NumberOfPeriods = atoi(m_NumberOfPeriods); double i = AnnualRate / CompoundType; int n = CompoundType * NumberOfPeriods; RatePerPeriod = AnnualRate / NumberOfPeriods; FutureValue = Principal * pow(1 + i, n); InterestEarned = FutureValue - Principal; m_InterestEarned.Format("$%.2f", InterestEarned); m_AmountEarned.Format("$%.2f", FutureValue); UpdateData(FALSE); }

10. Test the application
11. After using it, close it and return to your programming environment.