Question

I am trying to use the GetSystemWow64Direcory method from my application. The sample from PInvoke.net seems incorrect to me. Don’t I have to pin the the array before passing to the unmanaged call?

[DllImport("Kernel32.dll")]
public static extern int GetSystemWow64Directory([In, Out] char[] lpBuffer
    [MarshalAs(UnmanagedType.U4)] uint size);

char[] path = new char[256];

int result = GetSystemWow64Directory(path, (uint)path.Length);
if (result != 0)
    MessageBox.Show(new String(path, 0, result));

Answer 1

Well, you don’t need to pin, the marshaller will take care of that for you.

But, it’s a poor p/invoke. My advice is not to trust what you find on pinvoke.net, the quality is very varied. I’d use StringBuilder here.

[DllImport("kernel32.dll", CharSet=CharSet.Auto)]
public static extern int GetSystemWow64Directory(
    StringBuilder Buffer, 
    int Size
);
....
StringBuilder Buffer = new StringBuilder(260);
int retVal = GetSystemWow64Directory(Buffer, Buffer.Capacity);
if (retVal != 0)
    MessageBox.Show(Buffer.ToString());