On Error Goto 0 Vba Example
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minute: Sign up Why would you 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 app. Why would this ever be desirable? vb6 error-handling share|improve this question asked vba error handling best practices 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 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 commen
three flavors: compiler errors such as undeclared variables that prevent your code from compiling; user data entry error such as a user entering a negative value where only a positive number is acceptable; and run time errors, vba error handling in loop that occur when VBA cannot correctly execute a program statement. We will concern ourselves here
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only with run time errors. Typical run time errors include attempting to access a non-existent worksheet or workbook, or attempting to divide
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by zero. The example code in this article will use the division by zero error (Error 11) when we want to deliberately raise an error. Your application should make as many checks as possible during initialization http://stackoverflow.com/questions/9983464/why-would-you-ever-use-on-error-goto-0 to ensure that run time errors do not occur later. In Excel, this includes ensuring that required workbooks and worksheets are present and that required names are defined. The more checking you do before the real work of your application begins, the more stable your application will be. It is far better to detect potential error situations when your application starts up before data is change than to wait until later to encounter an http://www.cpearson.com/excel/errorhandling.htm error situation. If you have no error handling code and a run time error occurs, VBA will display its standard run time error dialog box. While this may be acceptable, even desirable, in a development environment, it is not acceptable to the end user in a production environment. The goal of well designed error handling code is to anticipate potential errors, and correct them at run time or to terminate code execution in a controlled, graceful method. Your goal should be to prevent unhandled errors from arising. A note on terminology: Throughout this article, the term procedure should be taken to mean a Sub, Function, or Property procedure, and the term exit statement should be taken to mean Exit Sub, Exit Function, or Exit Property. The term end statement should be taken to mean End Sub , End Function, End Property, or just End. The On Error Statement The heart of error handling in VBA is the On Error statement. This statement instructs VBA what to do when an run time error is encountered. The On Error statement takes three forms. On Error Goto 0 On Error Resume Next On Error Goto
generally put more focus on the coding part and getting the desired result but during this process we forget an important thing i.e. Error handling. http://www.exceltrick.com/formulas_macros/vba-on-error-statement/ Error handling is an important part of every code and VBA On Error Statement is an easy way for handling unexpected exceptions in Excel Macros. A well written macro is one that http://www.herongyang.com/VBScript/Error-Handling-On-Error-GoTo.html includes proper exception handling routines to catch and tackle every possible error. Error handling is important because in case of any unexpected exceptions your code doesn’t break. Even if any fatal unexpected on error error occurs in the code then also you should ensure that the code should terminate gracefully. Definition of VBA On Error Statement: On Error statement instructs VBA Compiler, what to do in case any runtime exception are thrown. Syntax of On Error Statement: Basically there are three types of On Error statement: On Error Goto 0 On Error Resume Next On Error Goto
a tutorial example on how to use 'On Error GoTo 0' to turn off the error handling flag in a procedure to catch the first runtime error. As you can see from the previous section, my last VBScript example reported the last runtime error, not the first one. If you want to catch the first runtime error is a large section of code, you need to: Enter the "On Error Resume Next" statement in the main code to turn on the error handling flag for the main code. Put that section of code into a new subroutine procedure. Enter the "On Error Goto 0" statement in the new procedure to turn off the error handling flag for that procedure. Check the Err.Number property right after calling that procedure. Here is the modified VBScript example to catch the first runtime error in a section of code:
Run this modified example code in IE, you will get: There is no error at this time. Before statement: x = 1/0 A runtime error has occurred: Err.Number = 11 Err.Description = Division by zero Err.Source = Microsoft VBScript runtime error What heppened was: When the first runtime error occurred on statement, x = 1/0, in the CodeToBeMonitored() procedure, execution stopped for that procedure, because the error handling flag was turned off for that procedure. Execution control was transferred back to the main code with the runtime error. Back in the main code, the execution continued beca