C# IntPtr vs ref string

[HavocXphere]

I'm trying to compile some code off MSDN its refusing to do so.

Basically the function requires a ref string while the value being used is a IntPtr. The compiler (VS Express '10) says it can't convert it.

// Call this function to remove the key from memory after use for security
[System.Runtime.InteropServices.DllImport("KERNEL32.DLL", EntryPoint="RtlZeroMemory")]
public static extern bool ZeroMemory(IntPtr Destination, int Length);

[...]

GCHandle gch = GCHandle.Alloc( sSecretKey,GCHandleType.Pinned );

[...]

ZeroMemory(gch.AddrOfPinnedObject(), sSecretKey.Length * 2);

As I understand it ref string and IntPtr are roughly the same thing, but I don't want to nuke the wrong memory location so a clean & correct conversion would be best.

Thanks
HX

 

[shogun]

I am compiling it without any problems here.

Have you modified it in any way?

 

[HavocXphere]

Weird. No, copied & pasted.

Uploaded it here under crypt.zip:
https://skydrive.live.com/?cid=5ca4ae2546c391e0&sc=documents&uc=1&id=5CA4AE2546C391E0!102#

 

[stevenv]

All the MSDN pages I look at indicate that GCHandle.AddrOfPinnedObject() returns an IntPtr which matches the signature of your extern method, so don't see why the compilation error.

http://msdn.microsoft.com/en-us/lib...es.gchandle.addrofpinnedobject(v=VS.100).aspx

Maybe it has something to do with your references, what's the fully-qualified type name of GCHandle?

 

[shogun]

Weird. No, copied & pasted.

Uploaded it here under crypt.zip:
https://skydrive.live.com/?cid=5ca4ae2546c391e0&sc=documents&uc=1&id=5CA4AE2546C391E0!102#

Not sure where you copy pasted from...

Yours:

public static extern bool ZeroMemory(ref string Destination, int Length);

Theirs (from the link you pasted):

public static extern bool ZeroMemory(IntPtr Destination, int Length);


EDIT: I see where you went wrong. You were being a good programmer and followed the whole document, building your source as you went along. Be a bad programmer and jump straight to the section called "Complete code listing" and copy that code... it's what compiles for me (uses IntPtr and not ref string)

 

[FarligOpptreden]

I say be the good programmer like you are and fight it out with Google links...

 

[HavocXphere]

EDIT: I see where you went wrong. You were being a good programmer and followed the whole document, building your source as you went along. Be a bad programmer and jump straight to the section called "Complete code listing" and copy that code... it's what compiles for me (uses IntPtr and not ref string)

Ah sneaky.

Compiles perfectly now. Thanks shogun!

 

[shogun]

Ah sneaky.

Compiles perfectly now. Thanks shogun!

No problem. There's nothing like a fresh pair of eyes.