LOTUSSCRIPT LANGUAGE


Examples: Function statement
Use a sub and a function to compute the cost of buying a house as follows:
Dim price As Single, message As String

Function Payment (princpl As Single, _
                 ByVal intrst As Single, _
                 ByVal term As Integer) As Single
  intrst! = intrst! / 12
  term% = term% * 12
  ' If any of the arguments are invalid, exit the function
  ' (payment will return the value 0).
  If princpl! <= 0 Or intrst! <= 0 Or term% < 1 Then _
     Exit Function
  ' The standard formula for computing the amount of the
  ' periodic payment of a loan:
  Payment = princpl! * intrst! / (1 - (intrst! + 1) ^ _
     (-term%))
End Function

Sub ComputeMortgageCosts (price As Single)
  Dim totalCost As Single, downpmt As Single
  Dim mortgage As Single, intrst As Single
  Dim monthlypmt As Single, years As Integer
EnterInfo:
  downpmt! = CSng(InputBox("How much is the down payment?"))
  ' The downpayment must be at least 10% of the price.
  If downpmt! < (0.1 * price!) Then
    MessageBox "Your down payment must be at least " _
        & Format(price! * .1, "Currency")
     GoTo EnterInfo
  Else
     mortgage! = price! - downpmt!
  End If
  intrst! = CSng(InputBox("What is the interest rate?"))
  years% = CInt(InputBox("How many years?"))
  ' Call the Payment function, which returns the
  ' monthly payment.
  monthlypmt! = Payment(mortgage!, intrst!, years%)
  totalCost! = downpmt! + (monthlypmt! * years% * 12)
  If monthlypmt! > 0 Then ' Create a multiline message.
     message$ = _  
      |Price | & Format(price!, "Currency") & |
      Down Payment: | & Format(downpmt!, "Currency") & |
      Mortgage: | & Format(mortgage!, "Currency") & |
      Interest: | & Format(intrst!, "Percent") & |
      Term: | & Str(years%) & |
      years Monthly Payment: | & Format(monthlypmt!, _  
      "Currency") & |
      Total Cost: | & Format(monthlypmt! * years% * 12, _  
       "Currency")
  Else
     message$ = "You did not enter valid input."
  End If
End Sub

' Start here.
price! = CSng(InputBox("How much does the house cost?"))
' Call the Compute MortgageCosts sub.
ComputeMortgageCosts (price!)
' Display the message.
MessageBox message$

See Also