在C＃中的指针检索参考从功能的DllImport

Question

我引用的DLL在我的C＃项目如下：

[DllImport("FeeCalculation.dll", CallingConvention = CallingConvention.StdCall,
           CharSet = CharSet.Ansi)]

        public static extern void FeeCalculation(string cin, string cout, string flimit,
            string frate, string fwindow, string fincrement, string fbird, 
            string fparameter, string fvalidation, string fcoupon);

在FeeCalculation功能如在DLL如下输出：

extern "C" __declspec(dllexport) void __stdcall FeeCalculation(char *cin, 
char *cout, char *flimit, char *frate,
char *fwindow, char *fincrement, char *fbird,
char *fparameter, char *fvalidation, char *fcoupon);

在DLL中的函数返回一个引用的内部结构，焦炭的形式*所以如果你要引用这个DLL在C ++中，你会做以下做计算，并获得返回的结构：

FeeCalculation(buff, (char *)&fans, (char *)fl, (char *)ft, (char *)fw, (char *)fi, (char *)fe, (char *)&fm, (char *)val, (char *)cpn);

现在，我该如何检索使用C＃返回的这些值的参考？意思是，我该怎么做在C＃一样的东西来获取返回的结构让我回来如何计算？我知道我需要创建一个不安全的方法，但我如何喜欢你用C ++会处理在C＃中的内存地址不清楚。

编辑：下面状态中使用的IntPtr但你怎么放进相同的结构，因此结构的字段可以被引用

编辑：这是返回结构我对（COUT）：

struct feeAnswer {


    unsigned int    fee;

    unsigned int    tax1;

    unsigned int    tax2;

    unsigned int    tax3;

    unsigned int    tax4;

    unsigned int    surcharge1;

    unsigned int    surcharge2;

    unsigned int    validationFee;

    unsigned int    couponFee1;

    unsigned int    couponFee2;

    unsigned int    couponFee3;

    unsigned int    couponFee4;

    unsigned short int dstay;       //Day Stay

    unsigned short int mstay;       //Minute Stay

};

下面是（CIN），我会一起传递与其它结构（它们是目前零字节，我想这首先工作，那么我将实施的其余部分）：

struct feeRequest {

    unsigned char   day;

    unsigned char   month;

    unsigned int    year;   //2000 ~ 2099



    unsigned char   hour;

    unsigned char   minute;

    unsigned char   rate;

    unsigned char   validation;



    unsigned char   coupon1;

    unsigned char   coupon2;

    unsigned char   coupon3;

    unsigned char   coupon4;

};

Answer 1

编辑：现在我们已经结构与工作，更好的解决方案是可能的。刚刚宣布在C＃结构匹配您的C ++结构这一点，在extern声明中使用它们

[StructLayout(LayoutKind.Sequential)]
public struct feeAnswer {
   public uint    fee;
   public uint    tax1;
   public uint    tax2;
   public uint    tax3;
   public uint    tax4;
   public uint    surcharge1;
   public uint    surcharge2;
   public uint    validationFee;
   public uint    couponFee1;
   public uint    couponFee2;
   public uint    couponFee3;
   public uint    couponFee4;
   public ushort  dstay;       //Day Stay
   public ushort  mstay;       //Minute Stay
   };

  [StructLayout(LayoutKind.Sequential, Pack=1)]
  public struct feeRequest {
   public byte   day;
   public byte   month;
   public uint   year;   //2000 ~ 2099
   public byte   hour;
   public byte   minute;
   public byte   rate;
   public byte   validation;
   public byte   coupon1;
   public byte   coupon2;
   public byte   coupon3;
   public byte   coupon4;
   };

  [DllImport ("FeeCalculation.dll", CallingConvention = CallingConvention.StdCall,
             CharSet = CharSet.Ansi)]
  public static extern void FeeCalculation (
          feeRequest cin,
          out feeAnswer cout,
           ...



        ....

原来的答复（之前，我们有结构）以下

---

在我看来，这些都不是内部串引用，而是指向字符串缓冲区，将在由呼叫来填补。如果你的返回的字符串指针，那么这些将被宣布char**而非char*。

所以我觉得这些只是标准输出参数。这里只是他们中的很多。所以，你的C＃互操作是这样的

[DllImport("FeeCalculation.dll", CallingConvention = CallingConvention.StdCall,
           CharSet = CharSet.Ansi)]
public static extern void FeeCalculation(string cin, 
        [MarshalAs(UnmanagedType.LPStr, SizeConst=100)]
        out string cout, 
        [MarshalAs(UnmanagedType.LPStr, SizeConst=100)]
        out string flimit,

或此，如果你的“弦”是不是真的字符串

[DllImport("FeeCalculation.dll", CallingConvention = CallingConvention.StdCall,
           CharSet = CharSet.Ansi)]
public static extern void FeeCalculation(string cin, 
        [MarshalAs(UnmanagedType.LPArray, SizeConst=100)]
        out byte[] cout, 
        [MarshalAs(UnmanagedType.LPArray, SizeConst=100)]
        out byte[] flimit,
        ....

Answer 2

在字符*在这种情况下的参数不是字符串而是指针表示数据的原始字节的块。您应该 Marshal.AllocHGlobal元帅的参数作为IntPtr的类型的实例，并结合以创建的存储器块，然后 Marshal.PtrToStructure 到该存储器块转换成可用的.NET类型。

作为一个例子：

[StructLayout(LayoutKind.Sequential)]
struct MyUnmanagedType
{
    public int Foo;
    public char C;
}

IntPtr memory = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(MyUnmanagedType)));

try
{
    FeeCalculation(memory);

    MyUnmanagedType result = (MyUnmanagedType)Marshal.PtrToStructure(
        memory, typeof(MyUnmanagedType));
}
finally
{
    Marshal.FreeHGlobal(memory);
}

Answer 3

要回答你的编辑，你需要创建一个结构，然后使用的 StructLayoutAttribute 上的字段，以使字节顺序和填充所述原来一样的dll一样。