C# 调用 C++ 类库的传参问题

最近经常用到 C# 调用 C++ 开发的动态类库,遇到了一些问题,多次尝试后终于解决了,这里简单的做下记录方便以后查询。

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 Windows 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);
posted @ 2012-09-20 16:55  Charles Zhang  阅读(80599)  评论(2编辑  收藏  举报