On Error Goto Msgbox Vb6
Contents |
Database Guide User login Username: * Password: * Request new password Home › Tutorials Error Handling In Visual Basic Level: Despite your best efforts to cover all possible contingencies, run-time errors will occur in
On Error Goto Line
your applications. You can and should do all you can to prevent them, but on error goto 0 when they happen you have to handle them. Introduction Trapping Errors at Run-Time Building Error Handlers Raising Your Own Errors on error exit sub Summary Introduction The various functions, statements, properties and methods available in Visual Basic and the components used in Visual Basic expect to deal with certain types of data and behavior in your applications. For
Vba Error Handling Best Practices
example, the CDate() function can convert a value to a Date variable. The function is remarkably flexible in the type of information it can accept, but it expects to receive data that it can use to derive a date. If you provide input that it can't convert, it raises error number 13 - "Type mismatch" - essentially saying "I can't handle this input data." In an application, this
On Error Goto 0 Vbscript
type of error may be a program logic error (you simply passed the wrong data) or it may be a data entry error on the part of the user (you asked for a date and the user typed a name). In the first case, you need to debug the program to fix the mistake. However, there is no way for you to anticipate the behavior of the end users of the application. If the user enters data you can't handle, you need to deal with the situation. Dealing with errors at run-time is a two step process: Trap the Error Before you can deal with an error, you need to know about it. You use VB's On Error statement to setup an error trap. Handle the Error Code in your error handler may correct an error, ignore it, inform the user of the problem, or deal with it in some other way. You can examine the properties of the Err object to determine the nature of the error. Once the error has been dealt with, you use the Resume statement to return control to the regular flow of the code in the application. In addition to dealing with run-time errors, you may at
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack vba error handling in loop Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack
Vba Error Number
Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Why would you try catch vba ever use “On Error Goto 0”? up vote 19 down vote favorite 5 Why would you ever use "On Error Goto 0" in a VB6 app? This statement turns the error handler off and would mean that any error would crash the http://www.vb6.us/tutorials/error-handling app. Why would this ever be desirable? vb6 error-handling share|improve this question asked Apr 2 '12 at 20:37 CJ7 4,99232114220 4 Well, it's certainly a way of implementing fail-fast –Greg Hewgill Apr 2 '12 at 20:39 I don't have VB6 installed, but presumably any Goto statement to a non-existant label would crash the app. –Sam Axe Apr 2 '12 at 20:40 This sounds like a comment from somebody who either throws in On Error Resume Next at the head of each http://stackoverflow.com/questions/9983464/why-would-you-ever-use-on-error-goto-0 procedure and then has mysterious woes that can't be diagnosed, or one who puts in On Error GoTo MyHandler and there just pops up a MsgBox with the same error anyway. –Bob77 Apr 2 '12 at 21:14 2 Not true at all. It is commonly paired with On Error Resume Next and a test of Err.Number to do inline structured error handling. –Bob77 Apr 3 '12 at 0:52 1 @CraigJ: Remember that the error handling is for that procedure (and children) only. "Turning it off" is NOT global, and allows errors to be handled by the parent. –Deanna Apr 3 '12 at 15:28 | show 9 more comments 4 Answers 4 active oldest votes up vote 35 down vote In VB6, you can specify that you want errors to be handled by particular code later in the routine: Sub Bar() On Error Goto MyHandler ... ...some code that throws an error... ... Exit Sub MyHandler: ...some error handler code (maybe pops up a dialog) End Sub It may be the case, however, that the code that throws the error is localized, and you don't want that same handler for all of the rest of the code in the routine. In that case, you'd use "On Error Goto 0" as follows: Sub Bar() ... On Error Goto MyHandler ...some code that throws an error... On Error Goto 0 ... ... Exit Sub MyHandler: ...some error handler code (maybe pops up a dialog) End Sub Now you have effectively scoped the error handling to execute on
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About http://stackoverflow.com/questions/9035664/confused-about-error-handling-in-vb6-and-the-use-of-on-error-goto Us Learn more about Stack Overflow the company Business Learn more about hiring http://www.vb-helper.com/tut6.htm developers or posting ads with us Stack Overflow Questions Jobs 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; it only takes a minute: Sign up Confused about Error Handling in VB6 on error 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 test with the On Error GoTo and the ErrHandler1, is that the ONLY line that's tested. Or will the divide on error goto 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: Call MsgBox(Err.Number & vbCrLf & Err.Description, vbExclamation, App.Title) share|improve this answer answered Jan 27 '12 at 15:48 Max 4,23511426 Thanks for the explanation! –JimDel Jan 27 '12 at 16:47 +1. The documentation explains this pretty clearl
explains the fundamentals of using error handlers in Visual Basic. There is a lot more to writing bug proof programs than just using error handlers. This book also explains how to reduce the chances of errors occurring in a program, how to detect errors when they do occur, and how to recover from unexpected errors. Visit the book's Web page to learn more. Chapter 12 Error Handling Fundamentals Sections Use On Error Leave Error Handlers Define Error Constants Keep Error Handlers Separate Understand Error Handler Scope Don't Nest Error Handlers Error Handling Slides This chapter explains the family of On Error statements Visual Basic uses to handle errors. It tells how a program installs and removes error handlers, and it explains some of the idiosyncrasies of error handling code. After reading this chapter you will be able to write basic error handlers to protect your programs from the unexpected. Use On Error A Visual Basic program uses the On Error statement to register error handling code. This statement can take one of three forms: On Error GoTo 0 On Error Resume Next On Error GoTo line These forms tell Visual Basic what it should do when the program encounters an error. The three forms are described in the following sections. On Error GoTo 0 On Error GoTo 0 is relatively straightforward. It simply cancels any currently installed error handler assigned by a previous On Error GoTo line or On Error Resume Next. If the program encounters an error after this statement executes, it crashes. On Error Resume Next On Error Resume Next makes the program ignore errors. When it encounters an error, the program continues execution after the statement that caused the error. When a program uses On Error Resume Next, it should check the Err object after every operation that might cause an error. If the value Err.Number is nonzero, the operation caused an error and the program can take special action. The program should check Err.Number immediately after the statement in question. Certain other actions reset the Err object and remove the previous error information. Many programs use On Error Resume Next when they present a common dialog to the user. The CommonDialog control's CancelError property indicates whether the control should raise an err