In exception handling, errors are dealt with in theCatchclause. To use it, on the right side ofCatch, type a parameter name, followed by the As operator, and followed by the the type of exception you want to deal with. By default, an exception is first of typeException. Based on this...
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...
Visual Basic supports structured exception handling, which you can use to create and maintain programs with robust, comprehensive error handlers. Structured exception handling is code designed to detect and respond to errors during execution by combining a control structure (similar to Select Case or ...
Exception handling is actually quite simple, and the following two paragraphs cover most of what you need to remember about it: When an exception is raised (usingthrow), the running program finds the nearest enclosingtryblock (propagating up the stack if necessary to find an enclosing try block...
If one of the catches matches the thrown error, its body executes. If noCatchmatches the thrown error, the compiler calls theExceptionclass and uses the default message Multiple catches are written if or when a try block is expected to throw different types of errors. For example, in our ...
Related Sections Exception and Error Handling in Visual Basic Lists links to topics related to exception handling in Visual Basic. Walkthrough: Structured Exception Handling Illustrates how to use the Try...Catch...Finally statement to handle exceptions.中文...
對應至此材質的範例應用程式ErrorHandling.sln包含表單frmErrors,可讓您試用此處所述的各種技術 (請參閱圖 1) 。 針對每個案例,請嘗試輸入不存在的檔案路徑,或不存在的磁片磁碟機,或不包含任何媒體的磁片磁碟機,或可能觸發檔案系統錯誤的任何其他路徑。
' Task IsCanceled: False ' Task IsFaulted: True ' Task Exception Message: One or more errors occurred. ' Task Inner Exception Message: Something happened. ' Output when an OperationCanceledException or TaskCanceledException ' is thrown in the awaited method: ' Exception Message: canceled ' Task...
The Base Case—No Error Handling at All What happens if your code includes no exception handling at all? In that case, any errors that occur at runtime bubble back up to the .NET runtime, and the runtime will greet your users with a confusing, and potentially dangerous, dialog box, sh...
语句没有 exception 变量,例如:Catch 当Try…Catch…Finally 嵌套在另一个 Try 块中时,Visual Basic 会首先检查最内层 Catch 块中的每个 Try 语句。 如果未找到匹配的 Catch 语句,则会继续搜索外层 Catch 块的Try…Catch…Finally 语句。 Try 块中的局部变量在 Catch 块中不可用,因为它们是单独的块。 如果要...