Get the size of an object (amount of memory it takes up).

[wyrd]

Is there a way to get the size of an object? C# has the sizeof() keyword, but unfortunately it only works for value types. I need something that'll work for reference types.

 

Meh, posted in wrong forum. Oh well. :)

[Nerseus]

I no of no way to get the size of a managed class.

Here's a blog from Microsoft that talks about this topic though - it might be helpful (I didn't read it through):

http://blogs.msdn.com/cbrumme/archive/2003/04/15/51326.aspx

 

Here's an article about memory, might also yield some results though again, I haven't read it:

http://www.albahari.com/value%20vs%20reference%20types.html

 

-ner

[wyrd]

I was afraid of that. I'll take a look at the links, thanks.

[dragon4spy]

For vb6, I can hack into memory and get the size by using ObjPtr() and CopyMemory(). But now vb.net doesn't support ObjPtr().

[Nerseus]

You can still pin memory and get a pointer to any managed object BUT to use copymemory you would have to know how big a chunk to copy. I think that's what wyrd is looking for.

 

If it's a simple class, you could try and "guess", but I because of byte alignment I don't know if there's any guarantee that your program won't change on a different platform (when 64bit computers are more normal for instance). Tough call.

 

-ner

[wyrd]

There just has to be a way to get the size of an object. :(

[Nerseus]

What object is it? If it's yours, why not just use a struct?

 

-Nerseus

[Derek Stone]

[msdn]System.Runtime.InteropServices.Marshal[/msdn].SizeOf()

[wyrd]

Unfortunately that method only works with an unmanaged object. And if I'm not mistaken, I'd have to allocated more memory in the unmanaged heap, get the size, then deallocate memory from the unmanaged heap, just to get the size (which isn't even accurate since it's the unmanaged size, and not the managed size).

 

It's not what I'm looking for, but thanks anyway.

[wyrd]

What object is it? If it's yours, why not just use a struct?

 

Of any managed object.

[Derek Stone]

Unfortunately that method only works with an unmanaged object. And if I'm not mistaken, I'd have to allocated more memory in the unmanaged heap, get the size, then deallocate memory from the unmanaged heap, just to get the size (which isn't even accurate since it's the unmanaged size, and not the managed size).

 

It's not what I'm looking for, but thanks anyway.

The method gets the equivalent unmanaged size of any CLR object (useful for platform invocation). It doesn't (and can't) get the size of an unmanaged object. This is the closest you're going to get to what you want.

[Nerseus]

From my limited digging, you just can't get the size of a managed class - at least through no publicly exposed interface anyone is talking about. Maybe there's a hidden API, but no one's talking.

 

I'm not sure if this will help, but you can get a pointer to any object through the use of a GCHandle object. Check the help on how to use it. Make sure you specify "pinned" memory when you create the handle and then you can safely pass the returned pointer (handle.AddrOfPinnedObject) to an API, if that's what you want/need.

 

-ner