[.net] Why can't DateTime.ParseExact() parse "9/1/2009" using "M/d/yyyy"

I have a string that looks like this: "9/1/2009". I want to convert it to a DateTime object (using C#).

This works:

DateTime.Parse("9/1/2009", new CultureInfo("en-US"));

But I don't understand why this doesn't work:

DateTime.ParseExact("9/1/2009", "M/d/yyyy", null);

There's no word in the date (like "September"), and I know the specific format, so I'd rather use ParseExact (and I don't see why CultureInfo would be needed). But I keep getting the dreaded "String was not recognized as a valid DateTime" exception.

Thanks

A little follow up. Here are 3 approaches that work:

DateTime.ParseExact("9/1/2009", "M'/'d'/'yyyy", null);
DateTime.ParseExact("9/1/2009", "M/d/yyyy", CultureInfo.InvariantCulture);
DateTime.Parse("9/1/2009", new CultureInfo("en-US"));

And here are 3 that don't work:

DateTime.ParseExact("9/1/2009", "M/d/yyyy", CultureInfo.CurrentCulture);
DateTime.ParseExact("9/1/2009", "M/d/yyyy", new CultureInfo("en-US"));
DateTime.ParseExact("9/1/2009", "M/d/yyyy", null);

So, Parse() works with "en-US", but not ParseExact... Unexpected?

I bet your machine's culture is not "en-US". From the documentation:

If provider is a null reference (Nothing in Visual Basic), the current culture is used.

If your current culture is not "en-US", this would explain why it works for me but doesn't work for you and works when you explicitly specify the culture to be "en-US".

Try

Date.ParseExact("9/1/2009", "M/d/yyyy", new CultureInfo("en-US"))

try this

provider = new CultureInfo("en-US");
DateTime.ParseExact("9/1/2009", "M/d/yyyy", provider);

Bye.

Set DateTimePicker's Format property to custom and CustomFormat prperty to M/dd/yyyy.

I tried it on XP and it doesn't work if the PC is set to International time yyyy-M-d. Place a breakpoint on the line and before it is processed change the date string to use '-' in place of the '/' and you'll find it works. It makes no difference whether you have the CultureInfo or not. Seems strange to be able specify an expercted format only to have the separator ignored.

Try :

Configure in web config file

<system.web> <globalization culture="ja-JP" uiCulture="zh-HK" /> </system.web>

eg: DateTime dt = DateTime.ParseExact("08/21/2013", "MM/dd/yyyy", null);

ref url : http://support.microsoft.com/kb/306162/