C#调用C++ DLL的难题

悬赏园豆：120 [已解决问题] 解决于 2012-01-12 23:44

请教大家一个问题，现在有个C++ PCIDLL.dll文件，在C#中调用 dll，出现错误如下：System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

请问C#代码哪里有误，烦请高手指点，谢谢！

C++ Code：

结构体：

typedef struct _DEV_CTRL_PARAM { intScanType;

intSelChannel[12];

intmParamType;

int*mEtalonPeakNum;

float*p_EtalonPeakVal;

}DEV_CTRL_PARAM,*PDEV_CTRL_PARAM;

externBOOL _stdcallPci_InitDevice(int mDev,PDEV_CTRL_PARAM pParam);

调用：

int mEtalonPeakNum = 0;

floatEtalonPeakVal[400];

DEV_CTRL_PARAM mParam;

int temptype[7] ={6,5,4,3,2,1,0};

mParam.ScanType=3;

mParam.mParamType = 0;
mParam.mEtalonPeakNum = &mEtalonPeakNum;

mParam.p_EtalonPeakVal = EtalonPeakVal;
mParam.SelChannel[0] = 1;

mParam.SelChannel[1] = 1;

mParam.SelChannel[2] = 1;

mParam.SelChannel[3] = 1;

mParam.SelChannel[4] = 1;

mParam.SelChannel[5] = 1;

mParam.SelChannel[6] = 1;

mParam.SelChannel[7] = 1;

mParam.SelChannel[8] = 1;

mParam.SelChannel[9] = 1;

mParam.SelChannel[10] = 0;

mParam.SelChannel[11] = 0;

Pci_InitDevice(0,&mParam);
----------------------------------------------------------------------------------

C# Code：

结构体：
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]

public struct DEV_CTRL_PARAM

{

[MarshalAs(UnmanagedType.I4)]

public int ScanType;

[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.I4, SizeConst = 12)]

public int[] SelChannel;

[MarshalAs(UnmanagedType.I4)]

public int mParamType;

[MarshalAs(UnmanagedType.I4)]

public int mEtalonPeakNum;

[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.R4, SizeConst = 400)]

public Single[] p_EtalonPeakVal;

}

[DllImport("PCIDLL.dll")]

public static extern bool Pci_InitDevice(int mDev, ref DEV_CTRL_PARAM pParam);

调用：

DEV_CTRL_PARAM mParam;

mParam.SelChannel = new int[12];
int mEtalonPeakNum = 0;

float[] EtalonPeakVal = new float[400];

int[] temptype = new int[7] { 6, 5, 4, 3, 2, 1, 0 };

mParam.ScanType = 3;

mParam.mParamType = 0;
mParam.mEtalonPeakNum = mEtalonPeakNum;

mParam.p_EtalonPeakVal = EtalonPeakVal;

mParam.SelChannel[0] = 1;

mParam.SelChannel[1] = 1;

mParam.SelChannel[2] = 1;

mParam.SelChannel[3] = 1;

mParam.SelChannel[4] = 1;

mParam.SelChannel[5] = 1;

mParam.SelChannel[6] = 1;

mParam.SelChannel[7] = 1;

mParam.SelChannel[8] = 1;

mParam.SelChannel[9] = 1;

mParam.SelChannel[10] = 0;

mParam.SelChannel[11] = 0;

Pci_InitDevice(0, ref mParam);

c# c++ dll

问题补充：

已将结构体修改为：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct DEV_CTRL_PARAM
{
public int ScanType;

[MarshalAs(UnmanagedType.ByValArray, SizeConst = 12, ArraySubType = UnmanagedType.I4)]
public int[] SelChannel;

public int mParamType;

public IntPtr mEtalonPeakNum;

public IntPtr p_EtalonPeakVal;

}

调用：

DEV_CTRL_PARAM mParam = new DEV_CTRL_PARAM();
mParam.SelChannel = new int[12];

int mEtalonPeakNum = 0;
float[] EtalonPeakVal = new float[400];
int[] temptype = new int[7] { 6, 5, 4, 3, 2, 1, 0 };

mParam.ScanType = 3;
mParam.mParamType = 0;

mParam.mEtalonPeakNum = new IntPtr(mEtalonPeakNum);

mParam.p_EtalonPeakVal = Marshal.UnsafeAddrOfPinnedArrayElement(EtalonPeakVal, 0);

mParam.SelChannel[0] = 1;
mParam.SelChannel[1] = 1;
mParam.SelChannel[2] = 1;
mParam.SelChannel[3] = 1;
mParam.SelChannel[4] = 1;
mParam.SelChannel[5] = 1;
mParam.SelChannel[6] = 1;
mParam.SelChannel[7] = 1;
mParam.SelChannel[8] = 1;
mParam.SelChannel[9] = 1;
mParam.SelChannel[10] = 0;
mParam.SelChannel[11] = 0;

请问红色部分还有其他写法？

C#S | 初学一级 | 园豆：44
提问于：2012-01-10 16:03

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最佳答案

使用结构是有点复杂，参考http://msdn.microsoft.com/zh-cn/library/aa686045.aspx 官方的说明

或者嫌麻烦可以使用一个工具，参考 http://www.cnblogs.com/lbq1221119/archive/2011/12/10/1040958.html 可以自动生成调用

这个错误的原因可能是结构的大小和指针的问题

http://stackoverflow.com/questions/941440/c-sharp-p-invoke-difficulties-marshalling-pointers

收获园豆：60

2012 | 高人七级 |园豆：21645 | 2012-01-10 17:32

谢谢您提供的资料和工具！

C#S | 园豆：44 (初学一级) | 2012-01-11 11:09

@小铭:

你的例子测试通过的代码：http://files.cnblogs.com/yeerh/PCallTest.7z

用MarshalAs，就是系统帮你包装而已，那些属性就是你告诉他要咱个封装。

如果理解了内存布局，就可以自己用指针写结构直接调用，那才是最方便快捷的。

边城浪 | 园豆：264 (菜鸟二级) | 2012-01-13 10:00

其他回答(6)

既然都有dll的C++源码，用VS跟踪进去可以调试的，或者用VC6也可以调试，看参数传进C++时，C++到底接收到什么数据。

咖啡色 | 园豆：208 (菜鸟二级) | 2012-01-10 17:00

这两个地方应该是指针的。你的结构定义有问题。

[MarshalAs(UnmanagedType.I4)]

public int mEtalonPeakNum;
[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.R4, SizeConst = 400)]

public Single[] p_EtalonPeakVal;

可以这样子

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    unsafe public struct DEV_CTRL_PARAM
    {
        public int ScanType;
        public int SelChannel0;
        public int SelChannel1;
        public int SelChannel2;
        public int SelChannel3;
        public int SelChannel4;
        public int SelChannel5;
        public int SelChannel6;
        public int SelChannel7;
        public int SelChannel8;
        public int SelChannel9;
        public int SelChannel10;
        public int SelChannel11;

        public int mParamType;
        public int* mEtalonPeakNum;
        public Single* p_EtalonPeakVal;
    }

调用：

[DllImport("PCIDLL.dll")]
public static extern bool Pci_InitDevice(int mDev, ref DEV_CTRL_PARAM pParam);

        unsafe static void Main(string[] args)
        {
            DEV_CTRL_PARAM mParam;
            int[] mEtalonPeakNum = new int[18];
            float[] EtalonPeakVal = new float[400];
            int[] temptype = new int[7] { 6, 5, 4, 3, 2, 1, 0 };
            mParam.ScanType = 3;
            mParam.mParamType = 0;
            mParam.SelChannel0 = 1;
            mParam.SelChannel1 = 1;
            mParam.SelChannel2 = 1;
            mParam.SelChannel3 = 1;
            mParam.SelChannel4 = 1;
            mParam.SelChannel5 = 1;
            mParam.SelChannel6 = 1;
            mParam.SelChannel7 = 1;
            mParam.SelChannel8 = 1;
            mParam.SelChannel9 = 1;
            mParam.SelChannel10 = 0;
            mParam.SelChannel11 = 0;

            fixed (int* d = mEtalonPeakNum)
            {
                fixed (float* dd = EtalonPeakVal)
                {
                    mParam.mEtalonPeakNum = d;
                    mParam.p_EtalonPeakVal = dd;
                    Pci_InitDevice(0, ref mParam);
                }
            }

            int count = sizeof(DEV_CTRL_PARAM);
            Console.WriteLine(count);
        }

收获园豆：30

边城浪 | 园豆：264 (菜鸟二级) | 2012-01-10 18:35

extern BOOL _stdcallPci_InitDevice(int mDev,PDEV_CTRL_PARAM pParam);

等价于：

[DllImport("PCIDLL.dll")]

static extern int Pci_InitDevice(int mDev, IntPtr pParam);

Launcher | 园豆：45050 (高人七级) | 2012-01-11 09:19

C++有许多优秀的类库，效率高，用C#是可以调用的，可以参考：http://www.docin.com/p-184985356.html，http://www.docin.com/p-271676146.html，http://www.docin.com/p-317759855.html，http://www.cnblogs.com/Jianchidaodi/archive/2009/03/11/1407270.html，http://blog.csdn.net/huwei2003/article/details/3882473等这些资料。需要注意数据类型的置换（指针和结构体），很多时候问题出现在这个地方。另外，还有一个思路，你可以参考：就是把进一步封闭C++DLL为webservice标准接口，这样无论什么样的语言都可以很好调用。稍后如果你仍没有解决，我给贴些例子。

收获园豆：30

lonely_rain | 园豆：752 (小虾三级) | 2012-01-12 09:37

[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct _DEV_CTRL_PARAM {

/// int
public int ScanType;

/// int[12]
[System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst=12, ArraySubType=System.Runtime.InteropServices.UnmanagedType.I4)]
public int[] SelChannel;

/// int
public int mParamType;

/// int*
public System.IntPtr mEtalonPeakNum;

/// float*
public System.IntPtr p_EtalonPeakVal;
}

keepsilence | 园豆：457 (菜鸟二级) | 2012-01-12 14:16

调DLL，还是用VB.Net来的方便，然后封装一下C#也可以调了。

Donaldxu | 园豆：207 (菜鸟二级) | 2012-01-12 15:12

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C#调用C++ DLL的难题

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