On Error In Vb6 With Example
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 your applications. You can and should do all you can to prevent them, but when on error vba they happen you have to handle them. Introduction Trapping Errors at Run-Time Building Error Handlers Raising
On Error Goto Line
Your Own Errors Summary Introduction The various functions, statements, properties and methods available in Visual Basic and the components used in Visual Basic expect to on error exit sub deal with certain types of data and behavior in your applications. For 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 on error goto 0 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 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
Vba Error Handling Best Practices
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 times want to generate them. This is often done in class modules built as components of ActiveX server DLLs or EXEs. It is considered good programming practice to separate the user interface from the program logic as much as possible, so if a server component cannot deal with an error, it should raise the error in its client application rather than simply display an error message for the user. In VB5, there is an option that allows you to specify that an application has been designed for unattended execution
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 vba on error goto 0 Us Learn more about Stack Overflow the company Business Learn more about hiring vba error handling in loop developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the
Vba Error Number
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 http://www.vb6.us/tutorials/error-handling 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 http://stackoverflow.com/questions/9035664/confused-about-error-handling-in-vb6-and-the-use-of-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 clearly... msdn.microsoft.com/en-us/library/aa266173(v=vs.60)
in many circumstances. For example, suppose you try to open a text file that the user has deleted. When a compiled program has an error like this, an error message isdisplayed and the program ends. Although you cannot predict and http://www.afralisp.net/archive/vba/error.htm write code for every possible type of error, "File Not Found" errors are fairly easy to handle. If you do not write code towork around the error, you can at least provide a message that makes more sense before ending the program. The "On Error" Statement The most common way to handle error conditions is to use Visual Basic's"On Error" statement.The "On Error" statement interrupts the normal flow of your program when an error occurs and on error begins executing your error handling code. A typical use is as follows :
On Error Goto FileOpenError When this statement is executed, any errors that occur in subsequentstatements cause Visual Basic to stop normal line-by-line execution andjump to the statement labeled as "FileOpenError". Labeling Code Lines Line labels in Visual Basic are similar to the line numbers of early BASIC.In Visual Basic, line labels can include text if you want, but each label mustbe unique. They on error goto are followed by a colon (:), as in the following example : Private Sub Form_Load () On Error Goto FileOpenError Open "C:\SOMEFILE.TXT" For Unput As #1 Line Input #1, sData Exit Sub FileOpenError: MsgBox "There was a problem opening the file. Stop for coffee!" End End Sub In the preceding sample code, if the "Open" or "Line Input" statements causean error, the statements starting at the label "FileOpenError" are executed,causing the message to be displayed and ending the program. You should note a few points about the sample code. First, note the locationand style of the error handling routine. It is usually placed near the end of thesubroutine, with the label not indented to indicate a special section of code. Second, and more important, note the "Exit Sub" statement after the "Open" statement. It is necessary to prevent the error handler routine from executingeven when the "Open" statement was successful. Controlling Program Flow After an Error In the preceding code example, you simply end the program if an error occurs. However, you can handle the error in several (better) ways : Exit the subroutine after informing the user of the error, and allow the program to continue running with limited functionality. Resume execution with the next statement following the error. Provide a way for the user to correct the error and retry the offending statement. You