On Error Resume Next Vbscript Scope
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LippertAugust 19, 200419 Share 0 0 OK, enough about the Peloponnesian war -- a number of readers have asked me questions about error handling in VBScript recently, so I think I'll talk about vbscript on error resume next it a bit for the next few days. Today, I want to very on error resume next vbscript w3schools carefully describe what the error handling semantics are in the language, because there is some confusion over how exactly
Error Handling In Vbscript Tutorial
it works. There are two statements that affect error handling in VBScript: On Error Resume NextOn Error Goto 0 The meaning of the first seems clear -- if you get an
Vbscript On Error Exit
error, ignore it and resume execution on the next statement. But as we'll see, there are some subtleties. But before that, what the heck is up with the second statement? The second statement turns off ‘resume next' mode if it is on. Yes, the syntax is ridiculous -- something like On Error Raise would be a whole lot more clear. But for historical purposes, vbscript error handling best practices this is what we're stuck with. Visual Basic has an error handling mode which VBScript does not -- VB can branch to a labeled or numbered statement. (Remember line numbers? Those were the days!) To tell VB that you no longer wish to branch to that statement, you give zero, an invalid line number. C'est super-beaucoup-de-fromage, n'est-ce pas? But we're stuck with it now. The subtlety in the "resume next" mode is best illustrated with an example. Const InvalidCall = 5Print "Global code start"Blah1Print "Global code end"Sub Blah1() On Error Resume Next Print "Blah1 Start" Blah2 Print "Blah1 End"End SubSub Blah2() Print "Blah2 Start" Err.Raise InvalidCall Print "Blah2 End"End Sub This prints out Global code startBlah1 StartBlah2 StartBlah1 EndGlobal code end Hold on a minute -- when the error happened, Blah1 had already turned ‘resume next' mode on. The next statement after the error raise is Print "Blah2 End" but that statement never got executed. What's going on? What's going on is that the error mode is on a per-procedure basis, not a global basis. (If it were on a global basis, all kinds of
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Vbscript Error Line Number
more about Stack Overflow the company Business Learn more about hiring developers or posting vbscript error message ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community if err.number 0 then 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 Try-Catch-End Try in VBScript up vote 22 down vote favorite https://blogs.msdn.microsoft.com/ericlippert/2004/08/19/error-handling-in-vbscript-part-one/ 6 I'm trying the following code: Try Throw 2 'How do I throw an exception? Catch ex 'What do I do here? End Try but I'm getting the error Statement expected in the catch clause. Does anyone know how I can catch/throw exceptions in VBScript using try/catch? (I am not looking for solutions with On Error Do X.) vbscript try-catch share|improve this question asked Feb 15 '11 at http://stackoverflow.com/questions/4999364/try-catch-end-try-in-vbscript 2:25 Mehrdad 104k64311617 3 Then you're going to be very disappointed. There's no Try-Catch support in pre-.NET versions of VB, including VB 6, VBA, and VBScript. On Error Resume Next isn't so bad if you know how to use it correctly. –Cody Gray Feb 15 '11 at 8:35 Yeah, I am disappointed. :( On Error Resume Next used to be my favorite command back in middle school, when I learned VB 6... it quickly became my most hated command after I learned C#. I guess I'll use it but I really don't want to. –Mehrdad Feb 15 '11 at 8:44 See below for some tips on using it correctly! :-) –Mark Ribau Sep 8 '11 at 5:30 add a comment| 4 Answers 4 active oldest votes up vote 16 down vote accepted VBScript doesn't have Try/Catch. (VBScript language reference. If it had Try, it would be listed in the Statements section.) On Error Resume Next is the only error handling in VBScript. Sorry. If you want try/catch, JScript is an option. It's supported everywhere that VBScript is and has the same capabilities. share|improve this answer answered Feb 15 '11 at 3:30 Tmdean 6,5002645 If it do
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 http://www.herongyang.com/VBScript/Error-Handling-On-Error-GoTo.html 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 on error 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 because the error handling flag was turned on for the main code. When Ch