How to pass null to a ref bool or out bool parameter?

[yyf]

Hi, How to pass null to a ref bool or out bool parameter? Thanks.

[Charlie Williams]

bool is a value type, therefore it cannot be null. bool is either true or false. There is no other state. By the way, when using out, the variable must be assigned a value before the method returns. The value of your variable going in wouldn't matter because it will be assigned a value before you get it back. Passing null (even if you could) wouldn't have any affect. Charlie if(!curlies){ return; }

[Judah Gabriel Himango]

FYI .NET 1.2, set to be beta'd this year and released next year, will utilize 1.2 generics feature for a Nullable value type, defined as Nullable<T>. This would allow you to pass a null value into a value parameter. See here[^] for more info. --------------------------- He who knows that enough is enough will always have enough. -Lao Tsu

[Heath Stewart]

It will be .NET 2.0, not 1.2. The file versions are only labeled as 1.2, just like the file versions for 1.1 are 1.1 but the assembly versions are still 1.0.5500.0. ".NET 2.0" is mentioned in many places on Microsoft et. al. sites.

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[Judah Gabriel Himango]

Oh really? I didn't know that; I knew C# would be C# 2.0, but I was under the impression it was .NET 1.2. --------------------------- He who knows that enough is enough will always have enough. -Lao Tsu

[Heath Stewart]

Here's one current reference: http://msdn.microsoft.com/vstudio/productinfo/roadmap.aspx#2005[^]. I believed they used ".NET 1.2" for a while but that started changing a few months ago. [EDIT] Oh, and rightly so. A LOT (as I'm sure you know) is changing between 1.1 and 2.0, unlikes the few changes between 1.0 and 1.1. It's still mostly backward compatible, but it includes a lot of bug fixes, performance enhancements, control adapters (new way to provide owner-drawing that's truly aweseom!), many new ASP.NET enhancements including some for WSS/SPS, and - of course - generics. [/EDIT]

Microsoft MVP, Visual C# My Articles

[partyganger]

There is some sourceForge project available that does implement just that. Nullable Value types. http://nullabletypes.sourceforge.net/ I wouldn't recommend it (if it's supposed to be a boolean, check for a boolean)

[leppie]

Try this:

void Foo(ref object boolean)
{
if (boolean == null) //blah blah
else
{
bool value = (bool) boolean;
}
}

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