unions in c#

Alan is right,

Thanks for pointing that out.

One thing which Mike's link didn't discuss was how to deal with unions of both value types and reference types (such as strings), bearing in mind that you're not allowed to overlap the two in .NET. The following link shows how to get around this restriction:

http://msdn2.microsoft.com/en-us/library/ya9bz4ha(vs.80).aspx 

If you don't mind using 'unsafe' code, then in C# 2.0 you can also use a fixed sized char buffer to represent a string within a union, as the buffer (rather than a pointer thereto) is actually embedded into the struct's memory and so is treated as a value type:

http://msdn2.microsoft.com/en-us/library/zycewsya(VS.80).aspx

Check out

http://msdn2.microsoft.com/En-US/library/acxa5b99(VS.80).aspx 

Best,