How to use a function pointer in C#

[Member 1033907]

Hi In my program I call a win32 API function which returns a function pointer as its result. How can I store and 'call' this pointer in C#? The API function in question is LRESULT SendMessage(...), which I map as IntPtr SendMessage(...). The function whose pointer is returned by SendMessage has the form int fn(void*, int); so I created a delegate delegate int RemoteFunction(IntPtr a, int b) and I try to convert the IntPtr (originally LRESULT) returned by SendMessage to an 'instance' of this delegate, like RemoteFunction x = (RemoteFunction) SendMessage(...); // compiler error So far I wasn't able to come up with a code that would at least compile, not to mention work. Do you have any suggestions? Any help appreciated, H.

[Rolando CC]

maybe this helps:

using System;
using System.Runtime.InteropServices;
namespace com_example
{
class Program
{
[DllImport("user32.dll")]
private static extern int MessageBox(IntPtr hWnd, String
text, String caption, uint type);

static void Main(string[] args)
{
MessageBox(
new IntPtr(0), "Hello, world!", "My box", 0);
}
}
}

[MidwestLimey]

Not tried it myself, but you could look into: System.Runtime.InteropServices.Marshal.GetDelegateForFunctionPointer. Supposedly converts an unmanaged fp into a delegate.

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[Member 1033907]

Thanks for you effort but this actually explains how to call an API function whose exact name I know at the design time. My question was rather how to call an external function that is returned dynamically (at runtime) in form of a function pointer. The post bellow explains this perfectly. Thanks anyway, H.

[Member 1033907]

Cool, I am sure this is it. Thank you very much! H.