I have a C api and I am using p/invoke to call a function from the api in my C# application. The function signature is:
int APIENTRY GetData (CASHTYPEPOINTER cashData); Type definitions:
typedef CASHTYPE* CASHTYPEPOINTER; typedef struct CASH { int CashNumber; CURRENCYTYPE Types[24]; } CASHTYPE; typedef struct CURRENCY { char Name[2]; char NoteType[6]; int NoteNumber; } CURRENCYTYPE; How would be my C# method signature and data types?
Thank you.
You need to specify the array sizes using SizeConst:
using System; using System.Runtime.InteropServices; public static class MyCApi { [StructLayout(LayoutKind.Sequential)] public struct CASHTYPE { public int CashNumber; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 24)] public CURRENCYTYPE[] Types; } [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct CURRENCYTYPE { [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 2)] public string Name; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 6)] public string NoteType; public int NoteNumber; } [DllImport("MyCApi.dll")] public static extern int GetData(ref CASHTYPE cashData); } I think it may look like this
using System.Runtime.InteropServices; [StructLayout(LayoutKind.Sequential)] public struct CASH{ public int CashNumber; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 24)] public CURRENCY Types[24]; } [ StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)] public struct CURRENCY { [MarshalAs( UnmanagedType.ByValTStr, SizeConst=2 )] public string Name; [MarshalAs( UnmanagedType.ByValTStr, SizeConst=6 )] public string NoteType; public int NoteNumber; } class Wrapper { [DllImport("my.dll")] public static extern int GetData(ref CASH cashData} } 
