Lesson 24: Errors Handling

Private Sub BtnCal_Click(sender As Object, e As EventArgs) Handles BtnCal.Click
    ' Hide previous error messages
    Lbl_ErrMsg.Visible = False
    
    Dim firstNum, secondNum As Double
    
    ' Set up error handling
    On Error GoTo error_handler
    
    ' Attempt to convert text to numbers
    firstNum = TxtNum1.Text
    secondNum = TxtNum2.Text
    
    ' Perform calculation
    Lbl_Answer.Text = firstNum / secondNum
    
    ' Exit before error handler if successful
    Exit Sub
    
error_handler:
    ' Display error message
    Lbl_Answer.Text = "Error"
    Lbl_ErrMsg.Visible = True
    Lbl_ErrMsg.Text = " One or both of the entries is/are non-numeric! Try again!"
End Sub

Private Sub BtnCal_Click(sender As Object, e As EventArgs) Handles BtnCal.Click
    Lbl_ErrMsg.Visible = False
    Dim firstNum, secondNum, answer As Double
    
    Try
        ' Attempt conversion and calculation
        firstNum = TxtNum1.Text
        secondNum = TxtNum2.Text
        answer = firstNum / secondNum
        Lbl_Answer.Text = answer
    
    Catch ex As Exception
        ' Handle any exceptions
        Lbl_Answer.Text = "Error"
        Lbl_ErrMsg.Visible = True
        Lbl_ErrMsg.Text = " One of the entries is not a number! Try again!"
        
        ' Optional: Log the error for debugging
        ' Debug.WriteLine("Error: " & ex.Message)
    End Try
End Sub

Try
    ' Code that might cause different exceptions
    
Catch ex As InvalidCastException
    ' Handle invalid type conversions
    MessageBox.Show("Please enter numeric values only")
    
Catch ex As DivideByZeroException
    ' Handle division by zero
    MessageBox.Show("Cannot divide by zero")
    
Catch ex As Exception
    ' Handle all other exceptions
    MessageBox.Show("An unexpected error occurred: " & ex.Message)
    
Finally
    ' Code that always runs (cleanup resources, etc.)
    ' e.g., connection.Close()
End Try