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Error-Handling, Debugging - Example - Simple Error Trapping

1. Start a new project. Add a text box and a command button.

2. Set the properties of the form and each control:

Form1:
BorderStyle - 1-Fixed Single
Caption - Error Generator
Name frmError

Command1:
Caption - Generate Error
Default - True
Name - cmdGenError

Text1:
Name - txtError
Text - [Blank]

The form should look something like this:



3. Attach this code to the cmdGenError_Click event.

Private Sub cmdGenError_Click()
On Error GoTo HandleErrors
Err.Raise Val(txtError.Text)
Err.Clear
Exit Sub

HandleErrors:
Select Case MsgBox(Error(Err.Number), vbCritical + vbAbortRetryIgnore, "Error Number" + Str(Err.Number))

Case vbAbort
  Resume ExitLine
Case vbRetry
  Resume
Case vbIgnore
  Resume Next
End Select

ExitLine:

Exit Sub
End Sub


In this code, we simply generate an error using the number input in the text box. The generic error handler then displays a message box which you can respond to in one of three ways.

4. Save your application. Try it out using some of these typical error numbers (or use numbers found with on-line help). Notice how program control changes depending on which button is clicked.

Error Number    Error Description

6                       Overflow
9                       Subscript out of range
11                     Division by zero
13                     Type mismatch
16                     Expression too complex
20                     Resume without error
52                     Bad file name or number
53                     File not found
55                     File already open
61                     Disk full
70                     Permission denied
92                     For loop not initialized


  

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