C#调用 C++编写的 DLL 函数各种参数传递问题 SendNewSms(char *szTel, char *szMessage); ----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 C#引用; [DllImport( "CdmaCard.dll",EntryPoint="SendNewSms")] public 2. 带返回值(char *) C++原型: extern static bool SendNewSms(string phone,string msg); 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 bool GetSmsSaveStation(ref int nStation); extern static 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; static int ReadUimAllBook([Out] UIM_BOOK_STRUCT [] }; [DllImport( "CdmaCard.dll",EntryPoint="ReadUimAllBook")] public lpUimBookItem,int nMaxArraySize); UIM_BOOK_STRUCT[] p = new UIM_BOOK_STRUCT[20]; int ret = ReadUimAllBook(p,p.Length); extern 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;