Possible Duplicate: Why use TryCast instead of DirectCast?
I want to know about TryCast
and DirectCast
in VB.NET. What is the difference between them?
The main difference between TryCast
and DirectCast
(or CType
) is that both CType
and DirectCast
will throw an Exception
, specifically an InvalidCastException
if the conversion fails. This is a potentially "expensive" operation.
Conversely, the TryCast
operator will return Nothing
if the specified cast fails or cannot be performed, without throwing any exception. This can be slightly better for performance.
The MSDN articles for TryCast
, DirectCast
and CType
say it best:
If an attempted conversion fails,
CType
andDirectCast
both throw anInvalidCastException
error. This can adversely affect the performance of your application.TryCast
returnsNothing
(Visual Basic), so that instead of having to handle a possible exception, you need only test the returned result against Nothing.
and also:
DirectCast
does not use the Visual Basic run-time helper routines for conversion, so it can provide somewhat better performance thanCType
when converting to and from data typeObject
.
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