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![Syntax of Try/Catch 18 Try [ try_Statement(s) ] [ Exit Try ] [ Catch [ exception_name [ As type ] ] [ When expression ] [ catch_Statement(s) ] [ Exit Try ] ] [ Catch ... ] [ Finally [ finally_Statement(s) ] ] End Try](https://image.slidesharecdn.com/vb-210526050548/75/Exception-Handling-in-VB-Net-18-2048.jpg)
Exception Handling in VB.Net
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- 2. C O N T E N T 01 Text Title Place yourown text here 02 Exception Handling 03 Unstructured Exception Handling 04 Types of Exception Handling 2 01 What is Exception? 05 Structured Exception Handling
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- 5. EXCEPTION An exception refersto a problem that arises during program execution. It is brought about by an unexpected circumstance. A good example is when you are performing a division operation, and then you divide by zero (0). An exception will be raised. 5
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- 7. Exception Handling 7 Exception handlingis the process of responding to the occurrence, during computation, of exceptions( anomalous or exceptional conditions requiring special processing ) often disrupting the normal flow of program execution.
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- 9. Types 9 There are twotypes of Exception Handling: ▪ Unstructured Exception Handling ▪ Structured Exception Handling
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- 11. Unstructured Exception Handling 11 There aretwo ways to handle excceptions in Unstructured way : if …else On Error GoTo Statement
- 12. On Error GoTo: Public Class Form1 Dim num1 As Integer Dim num2 As Integer Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim result As Integer On Error GoTo lbl num1 = CInt(TextBox1.Text) num2 = CInt(TextBox2.Text) funA() result = num1 num2 lbl: MsgBox(result) End Sub
- 13. If…else : Public ClassForm1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim array As Integer() = New Integer(3) {} array(0) = 10 array(1) = 20 array(2) = 30 array(3) = 40 For i As Integer = 0 To array.Length - 1 MessageBox.Show(array(i)) Next End Sub End Sub
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- 15. Structured Exception Handling 15 With exceptionhandling, you can transfer the control of a program from one part to another. In VB.NET, exceptions are handled in Structured way using 4 keywords:
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- 17. Keyword Detail Try The workof the Try block is to identify the code block for which a specific exception will be activated. It should be followed by a catch block(s). Catch Catching of the Exception is done in this block. It is an exception handler in which the Exception is handled. Finally Use the Finally block to run a set of statements whether an exception has occurred or not. Throw An exception is thrown after the occurrence of a problem. This is the work of the Throw keyword.
- 18. Syntax of Try/Catch 18 Try [try_Statement(s) ] [ Exit Try ] [ Catch [ exception_name [ As type ] ] [ When expression ] [ catch_Statement(s) ] [ Exit Try ] ] [ Catch ... ] [ Finally [ finally_Statement(s) ] ] End Try
- 19. Public Class Form1 Dimnum1 As Integer Dim num2 As Integer Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim result As Integer Try num1 = CInt(TextBox1.Text) num2 = CInt(TextBox2.Text) funA() result = num1 num2 Catch ex As DivideByZeroException MsgBox(ex.Message) Finally MsgBox(result) End Try End Sub Public Function funA() As Integer Dim result As Integer num1 = CInt(TextBox1.Text) num2 = CInt(TextBox2.Text) If num2 = 0 Then Throw New DivideByZeroException("plz enter denominator greater then 0") End If result = num1 num2 End Function End Class
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