Name
Try...Catch...Finally Statement
Syntax
TrytryStatements
[Catch1 [exception
[Astype
]] [Whenexpression
] catchStatements1 [Exit Try] Catch2 [exception
[Astype
]] [Whenexpression
]catchStatements2
[Exit Try] . . . Catchn [exception
[Astype
]] [Whenexpression
]catchStatementsn
] [Exit Try] [FinallyfinallyStatements
] End Try
Description
Used to handle runtime errors.
Rules at a Glance
The
tryStatements
, which are required, constitute theTry
block and are the statements that VB monitors for errors.The
Catch
blocks, of which there can be more than one, contain code that is executed in response to VB “catching” a particular type of error within theTry
block. Thus, theCatch
blocks consist of the error-handlers for theTry
block.The phrases
exception
[As
type
]
and[When
expression
]
are referred to as filters in the VB .NET documentation. In the former case,exception
is either a variable of type Exception, which is the base class that “catches” all exceptions, or a variable of one of Exception’s derived classes. TheWhen
filter is typically used with user-defined errors. (See the upcoming example.)The
Exit
Try
statement is used to break out of any portion of aTry...Catch...Finally
block.The optional
finallyStatements
code block is executed regardless of whether an error occurs (or is caught), unless anExit
Try
statement is executed.
Example
The code in the following Try
block will raise an
error if the user does not enter a number. The
Catch
block will catch this error.
Try Dim ...
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