Error Handling Functions In Vb
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Handling in Visual Basic Exception and Error Handling in Visual Basic Exception and Error Handling in Visual 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 vba error handling 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 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 rec
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.
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You can and should do all you can to prevent them, but when they error handling vbscript happen you have to handle them. Introduction Trapping Errors at Run-Time Building Error Handlers Raising Your Own Errors Summary Introduction The various error handling sql 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 https://msdn.microsoft.com/en-us/library/s6da8809(v=vs.100).aspx 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 http://www.vb6.us/tutorials/error-handling 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
at the time the application is being used. Some other problems could be caused by the computer on which the application is being http://www.functionx.com/visualbasic/exceptions/errorhandling.htm used. While developing your application, you should anticipate as many problems as http://www.garybeene.com/vb/tut-err.htm possible as take appropriate actions. Error Categories There are three main types of errors that could occur while your application is being used: Syntax Errors: A syntax error comes from your mistyping a word or forming a bad expression in your code. It could be that you misspelled a keyword error handling such as ByVel instead of ByVal. It could also be a bad expression. Examples are: 524+ + 62.55 if Number == 2 Number = 6 If you use the Microsoft Visual Basic IDE to write your code, it would point out the errors while you are writing your code, giving up time to fix them. There are other syntax errors that the IDE error handling functions may not detect. This could come from using a data type or class that doesn't exist. When you compile your application, the compiler can let you know about other syntax errors. Those types of errors are those the compiler cannot execute. It this case, the compiler intercepts, stops, and lets you know. For this reason, syntax errors are almost the easiest to fix. Most of the time, the compiler would point out where the problem is so you can fix it. Run-Time Errors: After all syntax errors have been fixed, the program may be ready for the user. The time period a person is using an application is called run-time. There are different types of problems that a user may face when interacting with your program. For example, imagine that, in your code, you indicate that a picture would be loaded and displayed to the user but you forget to ship the picture or the directory of the picture indicated in your code becomes different when a user opens your application. In this case, when you compiled and executed the application in your machine, everything was
SQL Advanced API Objects Internet File Transfers UNIX/CGI/Perl Perl Commands JavaScript Web Page Forms GBIC >> VB >> Tutorials >> Error Handling Error Handling The bottom line is that all of us make mistakes. VB is pretty clever about finding syntax errors within the IDE, but a number of the possible errors simply cannot be discovered until you try to run the program. This section discusses some of the available error detection and correction techniques. Users Hate Errors! If you make an error in VB, and you haven't written the code needed to respond to the error, do you know what happens? Well, VB simply puts up a message box saying there was an error. If you click on the OK button in the message then the VB program shuts down without saving anything that your user might have typed in. Let's be perfectly clear - This is not good! Your users will not like it and they will tell you about it. It's amazingly hard for a programmer to figure out how a user will mis-use the program. Actually, the term "mis-use" is not correct because the user will simply do whatever the application allows him to do. If the programmer didn't anticipate a particular input that can crash the program or if the programmer didn't anticipate a particular combination of entries that could also crash the program, then shame on the programmer! At a minimum, the programmer must allow for the possibility of an unknown error occurring and providing a means within the code to respond to the error, giving the user options to save (or not) any data already entered. Contrary to the contempt some programmers have for non-technical users, it is not acceptable practice to release programs which lose the user's data if he doesn't follow the user's manual. This is especially true because often a user's manual is ambigous, or written in techno-speak which the user might not understand. It's also not acceptable to include in the user's manual an instruction that says "Don't do this or the program will fail!". If the programmer knows of an input that will crash the program, it's his responsibili