On Error Goto Sample Code Vb6
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Database Guide User login Username: * Password: * Request new password Home › Tutorials Error handling in Visual Basic Level: Error handling is essential to all professional applications. Any number of run-time errors can occur, and if your program does not trap them, the VB default action is
On Error Goto Line
to report the error and then terminate the program (often resulting in the end user calling you on error exit sub and complaining, "Your program kicked me out!"). By placing error-handling code in your program, you can trap a run-time error, report it, and
On Error Goto 0
let the user continue. Sometimes the user will be able to correct the error and sometimes not, but simply allowing the program to crash is not acceptable. You should generally place error-handling code in any Sub or Function that accesses vba on error goto 0 files or databases. Your code will typically interrogate the Number and Description properties of the built-in VB Err object in an error-handling routine set up with the On Error statement. In this section, we will look at the following statements: On Error GoTo label On Error Resume Next Following is a brief tutorial in error-handling. To perform this tutorial, you should have a floppy disk handy. Also, in the VB IDE, make sure that the Break on Unhandled Errors vba error handling best practices option is set under Tools à Options à General. STEPS: 1. Start a new project. 2. Place four command buttons on the form. Name them and set their Captions as follows: Name Caption cmdCrash Crash cmdGoToLabel GoTo Label cmdGoTo0 GoTo 0 cmdResumeNext Resume Next Your form should look something like this: 3. Code the cmdCrash_Click event as follows: Private Sub cmdCrash_Click() Open "A:\JUNK.TXT" For Input As #1 MsgBox "File was opened successfully" Close #1 End Sub 4. Place your floppy disk in the A: drive. Run the program and click the Crash button. Assuming that you do not have a file called "JUNK.TXT" on your A: disk, the program will "bomb" with the code/message "53 – File Not Found". If you don't have a disk in drive A:, the code/message will be "71 – Disk Not Ready". 5. Code the cmdGoToLabel_Click event: Copy and paste the code from the Crash sub, and add statements so that the cmdGoToLabel_Click Sub looks like the following (the new statements are shown in bold): Private Sub cmdGoToLabel_Click() On Error GoTo OpenFileError Open "A:\JUNK.TXT" For Input As #1 MsgBox "File was opened successfully" Close #1 Exit Sub OpenFileError: MsgBox "The following error occured: " & vbNewLine _ & "Error # " & Err.Number & vbNewLine _ & Err.Description, _ vbCritical, _ "Open Error" End Sub 6. Run the program and click the "GoTo Label "button. Notice that
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Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; http://www.vb6.us/tutorials/error-handling-visual-basic it only takes a minute: Sign up Confused about Error Handling in VB6 and the use of On Error GoTo up vote 3 down vote favorite 1 I'm needing to troubleshoot some old VB6 code and I'm confused about the use of "On Error". In the sample below, if I surround the specific line of code I want to http://stackoverflow.com/questions/9035664/confused-about-error-handling-in-vb6-and-the-use-of-on-error-goto test with the On Error GoTo and the ErrHandler1, is that the ONLY line that's tested. Or will the divide by Zero be included if it's in the same Sub? On Error GoTo ErrHandler1 If Not Exists(BaseDirectory + "\ARCHIVE") Then _ MkDir BaseDirectory + "\ARCHIVE" ErrHandler1: Call MsgBox(Err.Number & vbCrLf & Err.Description, vbExclamation, App.Title) intValue1 = 12 intValue2 = 0 intValue3 = intValue1 / intValue Thanks. vb6 error-handling share|improve this question asked Jan 27 '12 at 15:25 JimDel 2,05453369 add a comment| 3 Answers 3 active oldest votes up vote 8 down vote accepted The divide by zero will be included and handled, and it will probably create a loop in your sample... The correct approach is like that On Error GoTo ErrHandler1 If Not Exists(BaseDirectory + "\ARCHIVE") Then _ MkDir BaseDirectory + "\ARCHIVE" On Error Goto 0 'this will un-hook you error handler intValue1 = 12 intValue2 = 0 intValue3 = intValue1 / intValue 'this will be an un-managed error Exit Sub 'this make sure that msgbox is shown only when the error happens ErrHandler1: C
Visual Basic 6 Code "On Error Resume Next" considered harmful By Palo Mraz, published on 21 Jan 2004 | Filed in Comments Visual Basic 6 http://www.developerfusion.com/code/4325/on-error-resume-next-considered-harmful/ SQL Server SQL As any seasoned VB programmer knows, the On Error Resume Next statement is used to check for errors the old (I might also say the C-style) way. When this statement is executed, any runtime error will be silently trapped and stored in the global Err object. We VB-ers typically use this construct to execute some "non-mission critical" code, on error where errors can be safely ignored. The canonical example I have seen many, many times, is the Form_Resize event handling procedure: Private Sub Form_Resize()
On Error Resume Next
' Resize the child controls on this form…
End Sub If this procedure did not contain the On Error Resume Next statement and a runtime error would on error goto occur, the application would be terminated with a nasty error message. (You do catch runtime errors in every event handling procedure, don't you?) In cases like this, the On Error Resume Next statement is quite handy, because it means less typing and more compact code. However, there are times, when this "handiness" might be very dangerous. The true danger of the On Error Resume Next statement lies in the fact that it makes it too easy to ignore the runtime errors. I have seen several cases, when ignoring runtime errors unintentionally was a recipe for disaster. Let me provide you with a real-life example taken from my own experience. Imagine a customer who had been using my application for several months and was happy with it. The application has a typical (somewhat boring:-) three-tier architecture (in the old days known as the Microsoft Windows DNA): VB6 front end; a typical forms-based application built with several 3rd party controls (GridEX, ActiveReports and AddFlow if you must know). VB6 back end; a DLL component configured to run as a COM+ application implementing the
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