Returning pointers from unmanaged to managed code

Question

I\'ve an unmanaged dll that exports the folowing function:

SomeData* test();

Let\'s assume SomeData as:

typedef struct          


        

Answer 1

When declaring the managed function you need to match pointer types with reference values or IntPtr values. In this case the LPStruct modifier won't help. The easiest solution is to convert the return value of test to be an IntPtr rather than SomeData since the native method is returning a pointer value. You can then write the following wrapper

[DllImport("DynamicLibrary.dll", CharSet=CharSet.Auto)]
public static extern IntPtr test();

public static SomeData testWrapper() {
  var ptr = test();
  try {
    return (SomeData)Marshal.PtrToStructure(ptr, typeof(SomeData));
  } finally {
    // Free the pointer here if it's allocated memory
  }
}