the managed PInvoke signature does not match the unmanaged target signature

Question

I'm having trouble when I ported this Interop Code from VB6 to C#

VB6:

Type Dpi_t
    dpiDrSuPsd(DPI_PRG_LEN) As Byte
    dpiMyPort               As Long
    dpiHostAdr(DPI_MAX_HOST) As Byte
    dpiHostCnt              As Integer
    dpiVoidCom              As Long
    dpiRspBdy               As Long
    dpiCmData               As Long
    dpiRdcxData             As Long
    dpiLstErr               As Long
    dpiONoUa                As Byte
    dpiOTooMuch             As Byte
    dpiOBar                 As Byte
    dpiVPin                 As Byte
    DpiPin                  As Long
    dpiCda(DPI_CDA_LEN)     As Byte
    dpiEcCyc(DPI_CYC_LEN)   As Byte
    dpitemp(6000)           As Byte
End Type

C#

    [StructLayout(LayoutKind.Sequential)]
    public struct Dpi_t
    {
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = DPI_PRG_LEN)]
        public byte[] dpiDrSuPsd;
        public long dpiMyPort;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = DPI_MAX_HOST)]
        public byte[] dpiHostAdr;
        public int dpiHostCnt;
        public long dpiVoidCom;
        public long dpiRspBdy;
        public long dpiCmData;
        public long dpiRdcxData;
        public long dpiLstErr;
        public byte dpiONoUa;
        public byte dpiOTooMuch;
        public byte dpiOBar;
        public byte dpiVPin;
        public long DpiPin;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = DPI_CDA_LEN)]
        public byte[] dpiCda;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = DPI_CYC_LEN)]
        public byte[] dpiEcCyc;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 6000)]
        public byte[] dpitemp;
    }

I can't get them to match, and I just ran out of ideas. What do you guys think?

Answer 1

I've never done VB6 to C# interop. But I think you are using the wrong C# data types in your .Net structure.

According to this summary of Visual Basic 6.0 data types a

1. VB6 Integer is 2 Bytes in size and a
2. VB6 Long is 4 Bytes in size.

So for a VB6 Integer you should use the short (Int16) data type and for Long you should use the int (Int32) data type.

Hope, this helps.