Get type of null array

Question

I'm working on some serialization routines, and I need a way to get the type of an input array.

Let's say I have the following object:

class myclass {
    public int foo;
    public byte[] bar;
}

Now I can get the type of myclass.foo by using GetType(). And if I say that "myclass.bar = new byte[0]", I can infer that bar is an array of bytes by using GetElementType(), HasElementType, and IsArray.

However if I never set bar and just leave it as null, I can't find a way to get the type info off the object. If I do myclass.foo.GetType() all I get is a null value.

Is there anyway to infer the type of "bar" in this case?

Here's a related post on SO: stackoverflow.com/questions/1120839/… — o.k.w
– o.k.w, Commented Nov 19, 2009 at 15:37

Mehrdad Afshari · Accepted Answer · 2009-11-19 15:20:10Z

5

A nonexistent object doesn't have a type. It doesn't make sense to get the type of a null reference. What you are looking for is actually the type of the field. You can get that by reflecting over the type declaring the field (in this case, myclass).

answered Nov 19, 2009 at 15:20

Mehrdad Afshari

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dsolimano · Accepted Answer · 2009-11-19 15:20:10Z

4

I think reflection should work -

typeof(myclass).GetField("bar").FieldType

answered Nov 19, 2009 at 15:20

dsolimano

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2 Comments

jonp Over a year ago

I don't get a NullReferenceException with that code, nor should you (unless the field doesn't exist, in which case Type.GetField(string) will return null, but as long as your names are correct you shouldn't get a NullReferenceException).

o.k.w Over a year ago

dsolimano's method should work, MSDN's reference has something similar: msdn.microsoft.com/en-us/library/t0cs7xez.aspx

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