C#调用C++编写的DLL函数各种参数传递问题

红太狼 2022-09-19 05:23 257阅读 0赞

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;

以下是几个简单的window调用

\[System.Security.SuppressUnmanagedCodeSecurity\] // We won't use this maliciously  
        \[DllImport("User32.dll", CharSet=CharSet.Auto)\]  
        public static extern bool ScreenToClient(IntPtr hWnd, ref System.Drawing.Point rect);

\[System.Security.SuppressUnmanagedCodeSecurity\] // We won't use this maliciously  
        \[DllImport("User32.dll", CharSet=CharSet.Auto)\]  
        public static extern bool GetWindowRect(IntPtr hWnd, out System.Drawing.Rectangle rect);

\[System.Security.SuppressUnmanagedCodeSecurity\] // We won't use this maliciously  
        \[DllImport("User32.dll", CharSet=CharSet.Auto)\]  
        public static extern bool UnregisterClass(\[MarshalAs(UnmanagedType.LPTStr)\] string className, IntPtr instanceHandle);