DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

String.IsNullOrEmpty - performance considerations, bugs

Technical Musings — Thu, 20 Nov 2008 16:07:34 GMT

I once read that .Net's String.IsNullOrEmpty performs better, and is safer, than just checking to see if a particular string has an empty value. I.e. replace if (myString == "") or if (myString.Equals(string.Empty)) or if (myString.Length == 0) with if

Controlling the usage of libraries

Community Blogs — Mon, 20 Oct 2008 18:26:32 GMT

Recently, Scott Hanselman has proposed a survey to know which part of the .NET Framework real-world developers

Controlling the usage of libraries

Patrick Smacchia [MVP C#] — Mon, 20 Oct 2008 17:48:01 GMT

Recently, Scott Hanselman has proposed a survey to know which part of the .NET real-world developers

El bug de String.IsNullOrEmpty en .NET 2.0

vtortola — Mon, 30 Jul 2007 19:11:31 GMT

Leo en un blog de MSMVPs.com una noticia de hace más de un año que contaba que se detecto un bug en el

Bug en String.IsNullOrEmpty en .NET 2.0

vtortola — Sun, 29 Jul 2007 23:58:06 GMT

Leo en un blog de MSMVPs.com que se ha detectado un bug en el método estático String.IsNullOrEmpty causado

dangerous behaviour of String.IsNullOrEmpty at www2.sitina.net

dangerous behaviour of String.IsNullOrEmpty at www2.sitina.net — Sun, 24 Jun 2007 05:25:23 GMT

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Okay this is nice, trust me | Suddenelfilio 's Blog

Okay this is nice, trust me | Suddenelfilio 's Blog — Wed, 20 Jun 2007 07:45:37 GMT

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String.IsNulOrEmpty Flaw

Dityo Nurasto Journal — Mon, 18 Jun 2007 16:12:32 GMT

String.IsNulOrEmpty Flaw

String.IsNullOrEmpty can lead to runtime Null exceptions!

DotNetKicks.com — Sun, 17 Jun 2007 14:23:39 GMT

You've been kicked (a good thing) - Trackback from DotNetKicks.com

Thomas goes .NET - String.IsNullOrEmpty() schmei??t Exceptions

Thomas goes .NET - String.IsNullOrEmpty() schmei??t Exceptions — Tue, 19 Sep 2006 13:34:47 GMT

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Be careful with String.IsNullOrEmpty

Jean-Paul Smit — Tue, 19 Sep 2006 09:07:45 GMT

While I ran FxCop over someone else's code it pointed me to a String method I didn't know about: IsNullOrEmpty

re: Null, Nothing, Empty

XTab's Blog — Thu, 06 Apr 2006 16:55:30 GMT

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

bill — Wed, 05 Apr 2006 23:34:22 GMT

Thanks Jonathan. I look forward to finding out why this happens.

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

Jonathan de Halleux — Wed, 05 Apr 2006 17:41:19 GMT

I am the tester for the JIT. We are looking at the problem since it is most likely a bug on our side.

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

Darren Kopp — Wed, 05 Apr 2006 16:13:06 GMT

very interesting. and to think that when you asked "have you spotted the problem?" all i could see was an if statement and a method call within a for loop :)

c# rules!

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

bill — Wed, 05 Apr 2006 06:36:14 GMT

Ayende,

I beleive that the removal of the code that checks for null is the likely suspect. It's that kind of optimisation that the JIT looks for when you allow it to optimise the code. Rember the JIT can inline code from other assemblies if it thinks it should.

I have bugged the issue on MSDN feedback:
http://lab.msdn.microsoft.com/productfeedback/viewfeedback.aspx?feedbackid=a184aa36-55d5-45d3-a308-9c2240a175fe

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

bill — Wed, 05 Apr 2006 06:34:08 GMT

Kalpesh, yes fo course you can assign a null to a string as it is a reference type.

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

Kalpesh — Wed, 05 Apr 2006 06:24:44 GMT

Well, this might sound stupid.

But, can you assign null to a string explicitly?

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

Ayende Rahien — Wed, 05 Apr 2006 05:56:39 GMT

This doesn't make sense.
The IsNullOrEmpty is a static method that is built correctly.
The exception is not caused on the IsNullOrEmpty, but on the test() method.
On the for() line, as a matter of fact, and I can't understand why.

re: DANGER ! String.IsNullOrEmpty can lead to runtime Null exceptions !!

bill — Wed, 05 Apr 2006 05:49:38 GMT

The JIT team hasn't officially said yet. My guess is that the JIT is removing the check for null on the parameter being passed to String.IsNullOrEmpty as this is often superfulous