Error Trapping In Vb 6.0
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 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 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 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,resources Windows Server 2012 resources Programs MSDN subscriptions Overview Benefits Administrators Students Microsoft Imagine Microsoft Student Partners ISV Startups TechRewards Events Community Magazine Forums Blogs Channel 9 Documentation APIs and reference Dev centers Retired content Samples We’re sorry. The content you requested has been removed. You’ll be auto redirected in 1 second. Using Visual Basic Programmer's Guide (All Editions) Part 2: What Can You Do With Visual Basic? Part 2: What Can You Do With Visual Basic? Debugging Your Code and Handling Errors Debugging Your Code and Handling Errors Debugging Your http://www.afralisp.net/archive/vba/error.htm Code and Handling Errors Creating a User Interface Using Visual Basic's Standard Controls More About Programming Programming with Objects Programming with Components Responding to Mouse and Keyboard Events Working with Text and Graphics Debugging Your Code and Handling Errors How to Handle Errors Designing an Error Handler Error Handling Hierarchy Testing Error Handling by Generating Errors Inline Error Handling Centralized Error https://msdn.microsoft.com/en-us/library/aa716196(v=vs.60).aspx Handling Turning Off Error Handling Error Handling with ActiveX Components Approaches to Debugging Avoiding Bugs Design Time, Run Time, and Break Mode Using the Debugging Windows Using Break Mode Running Selected Portions of Your Application Monitoring the Call Stack Testing Data and Procedures with the Immediate Window Special Debugging Considerations Tips for Debugging Processing Drives, Folders, and Files Designing for Performance and Compatibility International Issues Distributing Your Applications TOC Collapse the table of content Expand the table of content This documentation is archived and is not being maintained. This documentation is archived and is not being maintained. Visual Basic Concepts Visual Studio 6.0 Debugging Your Code and Handling Errors No matter how carefully crafted your code, errors can (and probably will) occur. Ideally, Visual Basic procedures wouldn't need error-handling code at all. Unfortunately, sometimes files are mistakenly deleted, disk drives run out of space, or network drives disconnect unexpectedly. Such possibilities can cause run-time errors in your code. To handle these errors, you need to add error-handling code to your procedures. Sometimes errors can also occur within your code; this t
resources Windows Server 2012 resources Programs MSDN subscriptions Overview Benefits Administrators Students Microsoft Imagine Microsoft Student Partners ISV Startups TechRewards Events Community Magazine Forums Blogs Channel 9 Documentation APIs https://msdn.microsoft.com/en-us/library/s6da8809(v=vs.100).aspx and reference Dev centers Retired content Samples We’re sorry. The content you requested has been removed. You’ll be auto redirected in 1 second. Visual Basic and Visual C# Visual Basic Developing Applications with Visual Basic Developing Applications with Visual Basic Exception and Error Handling in Visual Basic Exception and Error Handling in Visual Basic Exception and Error Handling in Visual error trapping Basic Using the Visual Basic Development Environment Programming in Visual Basic Development with My (Visual Basic) Accessing Data in Visual Basic Applications Debugging Your Visual Basic Application Exception and Error Handling in Visual Basic Introduction to Exception Handling (Visual Basic) Choosing When to Use Structured and Unstructured Exception Handling (Visual Basic) Types of Errors (Visual Basic) Configuring Warnings in Visual error trapping in Basic Structured Exception Handling in Visual Basic Unstructured Exception Handling in Visual Basic Add Imports Validation Error Dialog Box (Visual Basic) Add Imports Validation Error (Extension Methods) Dialog Box (Visual Basic) Deploying An Application (Visual Basic) Creating and Using Components in Visual Basic Printing and Reporting (Visual Basic) Going Further with Visual Basic Customizing Projects and Extending My with Visual Basic TOC Collapse the table of content Expand the table of content This documentation is archived and is not being maintained. This documentation is archived and is not being maintained. Exception and Error Handling in Visual Basic Visual Studio 2010 Other Versions Visual Studio 2008 Visual Studio 2005 Visual Studio .NET 2003 Visual Basic supports structured exception (error) handling, which allows the program to detect and possibly recover from errors during execution. Visual Basic uses an enhanced version of the Try...Catch...Finally syntax already supported by other languages such as C++. Structured exception handling combines a modern control structure (similar to Select Case or While) with exceptions, protected blocks of code, and filters.Structured exception handling, which is the