How can I pass a pointer to an array using p/invoke in C#?

Question

Example C API signature:

void Func(unsigned char* bytes);

In C, when I want to pass a pointer to an array, I can do:

unsigned ch         


        

Answer 1

The easiest way to pass an array of bytes is to declare the parameter in your import statement as a byte array.

[DllImport EntryPoint="func" CharSet=CharSet.Auto, SetLastError=true]
public extern static void Func(byte[]);

byte[] ar = new byte[1000];
Func(ar);

You should also be able to declare the parameter as an IntPtr and Marshal the data manually.

[DllImport EntryPoint="func" CharSet=CharSet.Auto, SetLastError=true]
public extern static void Func(IntPtr p);

byte[] ar = new byte[1000];
IntPtr p = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(byte)) * ar.Length);
Marshal.Copy(ar, 0, p, ar.Length);
Func(p);
Marshal.FreeHGlobal(p);