Finance Functions: The Number of Periods of an Investment

 The NumberOfPeriods() function calculates the number of periodic payments of an investment. Its syntax is: ```Extended __fastcall PeriodPayment(constExtended Rate, int Period, int NPeriods, const Extended PresentValue, const Extended FutureValue, TPaymentTime PaymentTime);``` Here is an example:
```//---------------------------------------------------------------------------
void __fastcall TForm1::btnCalculateClick(TObject *Sender)
{
Extended Present, Future, TheRate, Payments, NPeriod;

Present = StrToFloat(edtLoan->Text);
Future = StrToFloat(edtFuture->Text);
Payments = StrToFloat(edtPayments->Text);
TheRate = StrToFloat(edtRate->Text) / 12;

double Rate = TheRate / 100;
// Apply the function
NPeriod = NumberOfPeriods(Rate, -Payments, -Present,
Future, ptStartOfPeriod);
// Since the number of periods is really an integer, find its ceiling
Extended Actual = Ceil(NPeriod);
// Display the number of periods
edtNPeriods->Text = FloatToStr(Actual);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::btnExitClick(TObject *Sender)
{
PostQuitMessage(0);
}
//---------------------------------------------------------------------------```