C# unmanage DLL export

Hello
I have been trying to export a string array from my C# unmanged DLL export to metatrader , but can not do that , please need you expert suggestion ..

[DllExport("_CheckStringArray", CallingConvention = CallingConvention.StdCall)] public static void _CheckStringArray([In, Out, MarshalAs(UnmanagedType.LPStr)] StringBuilder [] str) { try { str[0].Append("hello"); } catch (Exception e) { MessageBox.Show(e.ToString()); } }

#import "CyboMySqlRead.dll" void _CheckStringArray(string s[]); //-- import end string array [3] ; //-- calling dll method , should update first index with "hello" _CheckStringArray(array) Print(array[0]); // nothing is printed here...