looking for simple vs2005 example, c# calling native c

Can someone point me to a tutorial or howto set up a vs2005 project that I can have a simple pocketPC c# project that calls a simple native c routine like:

#include < stdio.h>
void exchange ( int *a, int *b )
{
    int temp;
    temp = *a;
    *a = *b;
    *b = temp;
}

Thanks