What's the easiest way to verify the user had entered a valid date ?
28  2039 
"romy" <ro******@Power up1.com> schrieb What's the easiest way to verify the user had entered a valid date ?
Call Date.Parse in a Try/Catch block. If there's no excecption the date was
valid.
Armin
romy wrote: What's the easiest way to verify the user had entered a valid date ?
The IsDate() function.
--
Larry Lard
Replies to group please
"romy" <ro******@Power up1.com> schrieb: What's the easiest way to verify the user had entered a valid date ?
'Microsoft.Visu alBasic.Informa tion.IsDate'.
--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>
I recommend against this method in most cases; exceptions are
resource-intensive and shouldn't really be used for raw user-data
validation. It probably wouldn't matter much on a Win Forms app, but I
would really back away from this on ASP.NET if you're expecting any
volume of traffic.
The IsDate would be a better way to go.
Jason www.pettysconsulting.com
Armin Zingler wrote: "romy" <ro******@Power up1.com> schrieb
What's the easiest way to verify the user had entered a valid date ?
Call Date.Parse in a Try/Catch block. If there's no excecption the date
was valid.
Armin
Jason,
Doesn't IsDate use this same technique internally?
Kerry Moorman
"Jason Pettys" wrote: I recommend against this method in most cases; exceptions are
resource-intensive and shouldn't really be used for raw user-data
validation. It probably wouldn't matter much on a Win Forms app, but I
would really back away from this on ASP.NET if you're expecting any
volume of traffic.
The IsDate would be a better way to go.
Jason
www.pettysconsulting.com
Armin Zingler wrote: "romy" <ro******@Power up1.com> schrieb
What's the easiest way to verify the user had entered a valid date ?
Call Date.Parse in a Try/Catch block. If there's no excecption the date
was valid.
Armin
I'm not sure whether IsDate uses Exceptions as the primary mechanism.
Does anyone know for sure whether IsDate uses an exception for invalid
dates (1) always, (2) sometimes, or (3) never?
If I found out that it did I wouldn't use it; here's an msdn blog that
talks about it, the best quote being, "...pretend that the throw
statement makes the computer beep 3 times, and sleep for 2 seconds. If
you still want to throw under those circumstances, go for it." http://blogs.msdn.com/ricom/archive/.../19/44697.aspx
The feedback from Jeremy Wilson on this next page seems to indicate that
IsDate does not (or at least doesn't use it alone): http://blogs.crsw.com/mark/archive/2005/04/06/829.aspx
If I found out that IsDate DID rely primarily on an exception for
invalid values I would use something similar to that referenced in this
next article, the idea being to catch most invalid dates without
throwing an exception: http://searchvb.techtarget.com/vsnet...293037,00.html
Jason www.pettysconsulting.com
Kerry Moorman wrote: Jason,
Doesn't IsDate use this same technique internally?
Kerry Moorman
"Jason Pettys" wrote:
I recommend against this method in most cases; exceptions are
resource-intensive and shouldn't really be used for raw user-data
validation. It probably wouldn't matter much on a Win Forms app, but I
would really back away from this on ASP.NET if you're expecting any
volume of traffic.
The IsDate would be a better way to go.
Jason
www.pettysconsulting.com
Armin Zingler wrote:
"romy" <ro******@Power up1.com> schrieb
What's the easiest way to verify the user had entered a valid date ?
Call Date.Parse in a Try/Catch block. If there's no excecption the date
was valid.
Armin
Armin,
Call Date.Parse in a Try/Catch block. If there's no excecption the date
was valid.
This is what internally iw done in IsDate
(You can check it by setting the stop on all throwed events in the debugger)
:-)
Cor
"Jason Pettys" <pe****@nospam. nospam> schrieb: I'm not sure whether IsDate uses Exceptions as the primary mechanism. Does
anyone know for sure whether IsDate uses an exception for invalid dates
(1) always, (2) sometimes, or (3) never?
According to Lutz Roeder's Reflector, the method's implementation looks like
this:
\\\
Public Shared Function IsDate(ByVal Expression As Object) As Boolean
If (Not Expression Is Nothing) Then
If TypeOf Expression Is DateTime Then
Return True
End If
If TypeOf Expression Is String Then
Try
Dim time1 As DateTime =
DateType.FromSt ring(CType(Expr ession, String))
Return True
Catch exception1 As Exception
End Try
End If
End If
Return False
End Function
///
--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://classicvb.org/petition/>
Jason,
You can catch the exception that IsDate throws internally like this:
From the Debug menu choose Exceptions. Select Common Language Runtime
Exceptions. Select Break into the debugger when the exception is thrown.
Now run some code that calls IsDate with an invalid date. You should get
this message:
"A first chance exception of type 'System.FormatE xception' occurred in
mscorlib.dll
Additional information: The string was not recognized as a valid DateTime.
There is a unknown word starting at index 0."
So I am assuming that IsDate throws an exception internally when it is sent
an invalid date. Then IsDate catches the exception and returns False.
I guess the real proof would be to look at the IL code.
Kerry Moorman
"Jason Pettys" wrote: I'm not sure whether IsDate uses Exceptions as the primary mechanism.
Does anyone know for sure whether IsDate uses an exception for invalid
dates (1) always, (2) sometimes, or (3) never?
If I found out that it did I wouldn't use it; here's an msdn blog that
talks about it, the best quote being, "...pretend that the throw
statement makes the computer beep 3 times, and sleep for 2 seconds. If
you still want to throw under those circumstances, go for it."
http://blogs.msdn.com/ricom/archive/.../19/44697.aspx
The feedback from Jeremy Wilson on this next page seems to indicate that
IsDate does not (or at least doesn't use it alone):
http://blogs.crsw.com/mark/archive/2005/04/06/829.aspx
If I found out that IsDate DID rely primarily on an exception for
invalid values I would use something similar to that referenced in this
next article, the idea being to catch most invalid dates without
throwing an exception:
http://searchvb.techtarget.com/vsnet...293037,00.html
Jason
www.pettysconsulting.com
Kerry Moorman wrote: Jason,
Doesn't IsDate use this same technique internally?
Kerry Moorman
"Jason Pettys" wrote:
I recommend against this method in most cases; exceptions are
resource-intensive and shouldn't really be used for raw user-data
validation. It probably wouldn't matter much on a Win Forms app, but I
would really back away from this on ASP.NET if you're expecting any
volume of traffic.
The IsDate would be a better way to go.
Jason
www.pettysconsulting.com
Armin Zingler wrote:
"romy" <ro******@Power up1.com> schrieb
>What's the easiest way to verify the user had entered a valid date ?
>
>
Call Date.Parse in a Try/Catch block. If there's no excecption the date
was valid.
Armin This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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