Error Handling Functions Vba
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Vba Error Handling Exit Sub
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functions - Professional Excel Development Style up vote 5 down vote favorite 4 I got the book "Professional Excel Development" by Rob Bovey and it is opening up my eyes. I am refitting my code with error handling. However, there is a lot I don't understand. I especially need to know how to correctly use it in functions. I use Bovey's rethrow version of the error handler vba error handling display message (at bottom). When I started, I was using the basic boolean (non-rethrow) method and turned my subroutines into boolean functions. (P.S. I am switching back to the boolean method based on the answer.) I need guidance on how to fit functions into this scheme. I want them to return their real values (a string or double, e.g., or -1 if they fail in some cases) so I can nest them in other functions and not just return an error handling boolean. This is what a typical subroutine call to bDrawCellBorders(myWS) would look like within an entry point. Sub calls seem to be working well. (I.e. it is a subroutine that was turned into a function only so it can return a boolean to the error handling scheme.) Sub UpdateMe() ' Entry Point Const sSOURCE As String = "UpdateMe()" On Error GoTo ErrorHandler Set myWS = ActiveCell.Worksheet Set myRange = ActiveCell myWS.Unprotect ' lots of code If Not bDrawCellBorders(myWS) Then ERR.Raise glHANDLED_ERROR ' Call subroutine ' lots of code ErrorExit: On Error Resume Next Application.EnableEvents = True myWS.Protect AllowFormattingColumns:=True Exit Sub ErrorHandler: If bCentralErrorHandler(msMODULE, sSOURCE,,True) Then ' Call as Entry Point Stop Resume Else Resume ErrorExit End If End
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Time VBA - Arrays VBA - Functions VBA - SubProcedure VBA - Events VBA vba error handling in do while loop - Error Handling VBA - Excel Objects VBA - Text Files VBA - Programming Charts VBA - Userforms VBA Useful Resources vba error handling not working VBA - Quick Guide VBA - Useful Resources VBA - Discussion Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is Who VBA - Error Handling Advertisements http://stackoverflow.com/questions/19042604/vba-excel-error-handling-especially-in-functions-professional-excel-developm Previous Page Next Page There are three types of errors in programming: (a) Syntax Errors and (b) Runtime Errors (c) Logical Errors. Syntax errors Syntax errors, also called parsing errors, occur at interpretation time for VBScript. For example, the following line causes a syntax error because it is missing a closing parenthesis: Function ErrorHanlding_Demo() dim x,y x = "Tutorialspoint" y = Ucase(x End Function Runtime errors Runtime errors, also https://www.tutorialspoint.com/vba/vba_error_handling.htm called exceptions, occur during execution, after interpretation. For example, the following line causes a runtime error because here syntax is correct but at runtime it is trying to call fnmultiply, which is a non-existing function: Function ErrorHanlding_Demo1() Dim x,y x = 10 y = 20 z = fnadd(x,y) a = fnmultiply(x,y) End Function Function fnadd(x,y) fnadd = x+y End Function Logical errors Logic errors can be the most difficult type of errors to track down. These errors are not the result of a syntax or runtime error. Instead, they occur when you make a mistake in the logic that drives your script and you do not get the result you expected. You can not catch those errors, because it depends on your business requirement what type of logic you want to put in your program. For example, dividing a number by zero or a script that is written which enters into infinite loop. Err Object Assume if we have a runtime error, then the execution stops by displaying the error message. As a developer, if we want to capture the error, then Error Object is used. Example In the below example, Err.Number gives the error number and Err.Description gives error description. Err.Raise 6 ' Raise an overflow error
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, that occur when VBA cannot correctly http://www.cpearson.com/excel/errorhandling.htm execute a program statement. We will concern ourselves here only with run time errors. Typical run time errors include attempting to access a non-existent worksheet or workbook, or attempting to divide 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 to ensure that run time errors do not occur later. In Excel, error handling 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 error situation. If you have no error handling code and a run time error occurs, VBA will display vba error handling 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