Error Trapping In Visual Basic 6.0
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 they happen you have to handle them. Introduction Trapping Errors at Run-Time Building Error Handlers Raising 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 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 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 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 ra
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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 http://stackoverflow.com/questions/116289/what-is-the-better-way-to-handle-errors-in-vb6 us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up what is the better way to handle errors in VB6 up vote 12 down vote favorite 6 I have VB6 application , I want to put some good error handling finction in it which can tell me what was the error and exact error trapping place when it happened , can anyone suggest the good way to do this vb6 error-handling share|improve this question edited Sep 22 '08 at 17:36 Onorio Catenacci 9,01575386 asked Sep 22 '08 at 17:34 RBS 1,30192330 I removed the "in" tag. –Onorio Catenacci Sep 22 '08 at 17:36 I also changed the two separate "error" and "handling" tags to "error-handling" –Onorio Catenacci Sep 22 '08 at 17:37 add a comment| 7 Answers 7 active oldest votes up vote 2 down error trapping in vote accepted ON ERROR GOTO and the Err object. See this discussion. share|improve this answer answered Sep 22 '08 at 17:42 Joe Skora 8,97142430 add a comment| up vote 27 down vote First of all, go get MZTools for Visual Basic 6, its free and invaluable. Second add a custom error handler on every function (yes, every function). The error handler we use looks something like this: On Error GoTo {PROCEDURE_NAME}_Error {PROCEDURE_BODY} On Error GoTo 0 Exit {PROCEDURE_TYPE} {PROCEDURE_NAME}_Error: LogError "Error " & Err.Number & " (" & Err.Description & ") in line " & Erl & _ ", in procedure {PROCEDURE_NAME} of {MODULE_TYPE} {MODULE_NAME}" Then create a LogError function that logs the error to disc. Next, before you release code add Line Numbers to every function (this is also built into MZTools). From now on you will know from the Error Logs everything that happens. If possible, also, upload the error logs and actually examine them live from the field. This is about the best you can do for unexpected global error handling in VB6 (one of its many defects), and really this should only be used to find unexpected errors. If you know that if there is the possibility of an error occurring in a certain situation, you should catch that particular error and handle for it. If you know that an error occurring in a certain section is going to cause instability (File IO, Memory Issues, etc) warn the user and know that you are in an "unknown state