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POhow to pass an array of byte from C# to unmanaged C++, modify it on and pass it back to C#
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copied!<p>is it possible to pass a Byte[] from C# to unmanaged C++ and have it modified inside C++ reading its value back in C#? Something like:</p> <hr> <pre><code>C#: [DllImport("MyDll.dll")] public static extern bool UnmanagedFunction(ref Byte[] a, short b, ref ulong c); ... bool success; Byte[] a = new Byte[65]; ulong c = 0; success = UnmanagedFunction(ref a, (short)a.Length, ref c); </code></pre> <hr> <pre><code>C++: extern "C" __declspec(dllexport) BOOL WINAPI UnmanagedFunction( __inout_ecount(b) PBYTE a, __in INT16 b, __out DWORD c ) { BOOL success = FALSE; PBYTE uA; OVERLAPPED d; ... success = ReadFile( readHandle, uA, b, &c, &d); if ( success ) { a = uA; } free(uA); return success; } </code></pre> <hr> <p>When I try to read the variable "a" on C# after the invocation of "UnmanagedFunction" it shows only the first position of the array, I'm sorry about the C code I'm really new to pointers and references in C++</p> <p>I have tried to iterate through "uA" "c" times setting each position on "a", each position is defined but when the code returns to its managed section I get an exception telling me the memory is corrupt, something like:</p> <pre><code>for ( int i = 0; i < c; ++i ) a[i] = uA[i]; </code></pre> <p>I have seen functions returning an IntPtr and then invoking the Marshal.Copy on the managed side, but I was wondering if would it be possible to something close to what I'm trying to achieve above</p> <p>thanks in advance!</p>

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