Handling exception from unmanaged dll in C#

Answer 1

If the IntPtr result parameter is to receive the value from within the function, it must be marked ref.

I don't see ptrs[1] being assigned any value before passing.

Try changing the definition to:

[DllImport("Padeg.dll", EntryPoint = "GetNominativePadeg")]
private static extern Int32 decGetNominativePadeg(IntPtr surnameNamePatronimic,
    **ref** IntPtr result, ref Int32 resultLength);

The reason probably is that it's trying to write to "result" which is marked as input-only.

Answer 2

Hello, you have probably turned off debugging of unmanaged code.

"Enable unmanaged code debugging option" must be check in project properties under the Debug section. After this, the exception is shown in the debugging process.

Answer 3

Problem solved. I found out that when using 4-th framework I have this problem, when using 3.5 - I don't.