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This small application shows how to calculate the
compound interest of a saving.
Prerequisites:
When you deposit money in a savings account, your
money earns interest that is calculated every month or quarter, etc.
Because this is not money you need right away, the amount accrued can be
reinvested, thus boosting your interest so the next calculation would be
based on the original amount plus the new added value. This is the basis
of compound interest. The compound interest can be
calculated monthly or quarterly, etc based on the original amount you
deposited, the interest rate, and the period you and the institution agreed
upon. |
This application uses a dialog box equipped with the
necessary controls used to perform the type or related calculated. The
formula we will use to perform the calculations is as follows:
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P = Principal |
| r = Annual (Interest) Rate |
| m = Number of Compounding Periods per Year |
| n = Total Number of Compounding Periods |
| A = Amount Earned After n periods |
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 Practical Learning: Starting the Exercise
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- Start Microsoft Visual C++ 2005
- Create a new CLR Windows Forms Application named CompoundInterest1
- Design the form as follows:
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| Control |
Name |
Text |
Additional Properties |
| Form |
|
Compound Interest |
MaximizeBox: False |
| GroupBox |
|
Preparation |
|
| Label |
|
Principal: |
|
| TextBox |
txtPrincipal |
0.00 |
TextAlign: Right |
| Label |
|
Interest Rate: |
|
| TextBox |
txtInterestRate |
0.00 |
TextAlign: Right |
| Label |
|
% |
|
| Label |
|
Number of Periods: |
|
| TextBox |
txtPeriods |
1 |
TextAlign: Right |
| Label |
|
Years |
|
| GroupBox |
|
Compound Frequency |
|
| RadioButton |
rdoMonthly |
Monthly |
CheckAlign: MiddleRight |
| RadioButton |
rdoQuarterly |
Quarterly |
CheckAlign: MiddleRight |
| RadioButton |
rdoSemiannually |
Semiannually |
CheckAlign: MiddleRight |
| RadioButton |
rdoAnnually |
Annually |
CheckAlign: MiddleRight |
| Button |
btnCalculate |
Calculate |
On the form, set AcceptButton:
btnCalculate |
| Button |
btnClose |
Close |
On the form, set
CancelButton: btnClose |
| GroupBox |
|
Results |
|
| Label |
|
Interest Earned: |
Align Text: Right |
| TextBox |
txtInterestEarned |
0.00 |
TextAlign: Right |
| Label |
|
Amount Earned: |
|
| TextBox |
txtAmountEarned |
0.00 |
TextAlign: Right |
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- On the form, double-click the Calculate button and implement its
OnClick() event as follows:
System::Void btnCalculate_Click(System::Object^ sender,
System::EventArgs^ e)
{
double Principal, AnnualRate, InterestEarned;
double FutureValue, RatePerPeriod;
int NumberOfPeriods, CompoundType;
Principal = double::Parse(txtPrincipal->Text);
AnnualRate = double::Parse(txtInterestRate->Text) / 100;
if( rdoMonthly->Checked )
CompoundType = 12;
else if( rdoQuarterly->Checked )
CompoundType = 4;
else if( rdoSemiannually->Checked )
CompoundType = 2;
else
CompoundType = 1;
NumberOfPeriods = int::Parse(txtPeriods->Text);
double i = AnnualRate / CompoundType;
int n = CompoundType * NumberOfPeriods;
RatePerPeriod = AnnualRate / NumberOfPeriods;
FutureValue = Principal * Math::Pow(1+i, n);
InterestEarned = FutureValue - Principal;
txtInterestEarned->Text = InterestEarned.ToString("C");
txtAmountEarned->Text = FutureValue.ToString("C");
}
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- On the form, double-click the Close button and implement its OnClick()
event as follows:
System::Void btnClose_Click(System::Object^ sender,
System::EventArgs^ e)
{
Close();
}
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- Test the application
- After using it, close it and return to your programming environment
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