Public Class Tester
Public Shared Sub Main
Try
Console.WriteLine(SquareRoot(123.123))
Console.WriteLine(SquareRoot(-123.123))
Catch formatException As FormatException
Console.WriteLine(formatException.Message)
Catch negativeNumberException As _
NegativeNumberException
Console.WriteLine(negativeNumberException.Message)
End Try
End Sub
Public Shared Function SquareRoot(ByVal operand As Double) As Double
If operand < 0 Then
Throw New NegativeNumberException( _
"Square root of negative number not permitted")
End If
Return Math.Sqrt(operand)
End Function ' cmdSquareRoot
End Class
Public Class NegativeNumberException
Inherits ApplicationException
Public Sub New()
MyBase.New("Illegal operation for a negative number")
End Sub ' New
Public Sub New(ByVal messageValue As String)
MyBase.New(messageValue)
End Sub ' New
Public Sub New(ByVal messageValue As String, _
ByVal inner As Exception)
MyBase.New(messageValue, inner)
End Sub
End Class
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