最近經常用到 C# 調用 C++ 開發的動態類庫,遇到了一些問題,多次嘗試后終於解決了,這里簡單的做下記錄方便以后查詢。
1、不返回值的參數
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、帶返回值(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 大小必須大於可能的最大長度 GetCardErrorMessage(buf,1);
3、帶返回值(其他類型)
C++ 原型:
BOOL GetSmsSaveStation (int *nSmsStation);
C# 引用:
[DllImport( "CdmaCard.dll",EntryPoint="GetSmsSaveStation")] public static extern bool GetSmsSaveStation(ref int nStation);
4、傳遞結構體指針(C++ 填充)
C++ 原型:
struct NET_INFO_STRUCT { DWORD nDurationTime; //持續時間 double nReceiveByte; //接收字節 double nSendByte; //發送字節 }; BOOL NetGetConnectDetail(NET_INFO_STRUCT *lpNetInfo);
C# 引用:
public struct NET_INFO_STRUCT { public uint nDurationTime; //持續時間 public double nReceiveByte; //接收字節 public double nSendByte; //發送字節 } [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、傳遞結構體數組(C++ 來填充)
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)]//可以指定編碼類型 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、注意問題
類型不一致,會導致調用失敗:
(1)、 long 類型,在 C++ 中是 4 字節的整數,在 C# 中是 8 字節的整數;
(2)、字符串類型的設置不正確;
以下是幾個簡單的 Windows 調用:
[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);