Question

I have a function definition in my VC++ Win32 DLL

DEMO2_API void ProcessData(char* i_buff, unsigned short i_len, char* o_buf,
unsigned *o_len, unsigned short *errorCode)
{
    __describe (i_buff,&i_len,o_buf,o_len,errorCode);
}

This dll function is called by a c# application.
When called, it generate access violation exception.

After reasearching i found, the cause for my problem.

http://social.msdn.microsoft.com/Forums/en-US/csharplanguage/thread/6e843243-baf4-4eb1-8a20-c691ad47762c

But could not understand what exactly they are doinng in example code.
Can someone explain it so me?

And what would be P/Invoke signature in c# after externally allocating memory?

Answer 1

I changed passing mode of O_len to out instead of ref and it works.

Thnaks everyone for giving nice answers and comments. I hope this would be useful for other community members ( plus those googling…)