C#调用C++编写的DLL函数各种参数传递问题

----在网上查了一个星期,终于找到解决方法

1. 不返回值的参数

C++ 原型:

bool SendNewSms(char *szTel, char *szMessage);

C#引用;

[DllImport( "CdmaCard.dll",EntryPoint="SendNewSms")] public static extern bool SendNewSms(string phone,string msg);

2. 带返回值(char *)

C++原型:

BOOL GetCardErrorMessage(char *szErrorMessage , int errorCode);

C#引用

[DllImport( "CdmaCard.dll",EntryPoint="GetCardErrorMessage")] public static extern int GetCardErrorMessage(StringBuilder msg,int errorCode);

StringBuilder buf = new StringBuilder(1024);//指定的Buf大小必须大于可能的最大长度 GetCardErrorMessage(buf,1);

3. 带返回值(其他类型)

C++原型:

BOOL GetSmsSaveStation (int *nSmsStation);

C#引用

[DllImport( "CdmaCard.dll",EntryPoint="GetSmsSaveStation")] public static extern bool GetSmsSaveStation(ref int nStation);

4. 传递结构体指针(C++填充) C++原型: struct NET_INFO_STRUCT { DWORD nDurationTime; //持续时间 double nReceiveByte; //接收字节 double nSendByte; //发送字节 }; BOOL NetGetConnectDetail(NET_INFO_STRUCT *lpNetInfo); C#引用 public struct NET_INFO_STRUCT { public uint nDurationTime; //持续时间 public double nReceiveByte; //接收字节 public double nSendByte; //发送字节 } [DllImport( "CdmaCard.dll",EntryPoint="NetGetConnectDetail")] public static extern int NetGetConnectDetail(ref NET_INFO_STRUCT pNetInfo); NET_INFO_STRUCT netInfo = new NET_INFO_STRUCT(); NetGetConnectDetail(ref netInfo);

5. 传递结构体数组(C++来填充) C++原型: struct UIM_BOOK_STRUCT { int UimIndex; char szName[15]; char szPhone[21]; }; int ReadUimAllBook(UIM_BOOK_STRUCT lpUimBookItem[],int nMaxArraySize);

C#引用 [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]//可以指定编码类型 public struct UIM_BOOK_STRUCT { public int UimIndex; [MarshalAs(UnmanagedType.ByValTStr, SizeConst= 15)] public string szName; [MarshalAs(UnmanagedType.ByValTStr, SizeConst= 21)] public string szPhone; };

[DllImport( "CdmaCard.dll",EntryPoint="ReadUimAllBook")] public static extern int ReadUimAllBook([Out] UIM_BOOK_STRUCT [] lpUimBookItem,int nMaxArraySize);

UIM_BOOK_STRUCT[] p = new UIM_BOOK_STRUCT[20]; int ret = ReadUimAllBook(p,p.Length);

6. 注意问题 类型不一致,会导致调用失败, (1) long 类型,在C++中是4字节的整数,在C#中是8字节的整数; (2) 字符串类型的设置不正确;