如何将结构指针从 c# 传递到 win32 DLL

Question

我想将字节数组从 C# 传递到 win32 DLL 以用于 c++ 中的某些进程！

我的 C++ 代码

    typedef struct
    {
        int length;
         unsigned char value[10000000];
    } wavfile;

    extern "C" __declspec(dllexport) int insert_In_Table(wavfile *w)
   {

    hashing HS( w->value , (unsigned int)w->length);

        return HS.insertIn_hashTable();
    }

和我的 C#

[DllImport("HashCplusDll.dll" , CallingConvention=CallingConvention.Cdecl)]
public static extern int insert_In_Table(ref Wavfile sample);
public static int recordNumber_old = 0;

public struct Wavfile
{

    public int length;
    [MarshalAs(UnmanagedType.LPArray, SizeConst = 10000000)]
    public byte[] value;
}

public void button1_Click(object sender, EventArgs e)
{
    // open file dialog 
    OpenFileDialog open = new OpenFileDialog();
    open.Filter = "All files (*.*)|*.*"; 
    if (open.ShowDialog() == DialogResult.OK)
    {

        string location = open.FileName;
        byte[] array = System.IO.File.ReadAllBytes(location);
        textBox1.Text = location;

        Wavfile pass = new Wavfile();
        pass.value = array;
        pass.length = array.Length;
        int numberOfRow = insert_In_Table(ref pass);
    }

但是我有这个错误

A first chance exception of type 'System.TypeLoadException' occurred in WindowsFormsApplication1.exe

Additional information: Cannot marshal field 'value' of type 'Wavfile': Invalid managed/unmanaged type combination (Array fields must be paired with ByValArray or SafeArray).

If there is a handler for this exception, the program may be safely continued.

我尝试了一些解决方案，例如 out 而不是 ref，但仍然无法运行应用程序。

我该怎么办？

Answer 1

由于 MarshallAs 的元属性，它正在抱怨。您需要将其更改为 ByValArray。

而不是 UnmanagedType.LPArray 使用 UnmanagedType.ByValArray

Answer 2

我通过将值字段更改为指针解决了这个问题

c++

typedef struct
{
    int length;
    unsigned char* value;
} wavfile;

extern "C" __declspec(dllexport) int insert_In_Table(wavfile *w)
{

    hashing HS( w->value , (unsigned int)w->length);

    return HS.insertIn_hashTable();
}

c#

[DllImport("C:\...\HashCplusDll.dll", CallingConvention= CallingConvention.Cdecl)]
        public static extern int insert_In_Table(ref Wavfile sample);
        public static int recordNumber_old = 0;
        //StructLayout(LayoutKind.Sequential)]
        public struct Wavfile
        {

            public int length;
            public IntPtr value;
        }

        public void button1_Click(object sender, EventArgs e)
        {
            // open file dialog 
            OpenFileDialog open = new OpenFileDialog();
            open.Filter = "All files (*.*)|*.*";
            if (open.ShowDialog() == DialogResult.OK)
            {

                string location = open.FileName;
                byte[] array = System.IO.File.ReadAllBytes(location);
                textBox1.Text = location;

                Wavfile pass = new Wavfile();

                pass.length = array.Length;
                pass.value = Marshal.AllocHGlobal(array.Length);
                Marshal.Copy(array, 0, pass.value, array.Length);
                // Call unmanaged code
                int numberOfRow = insert_In_Table(ref pass);
}

如何将结构指针从 c# 传递到 win32 DLL

how to pass a struct pointer from from c# to win32 DLL

c#

c++

dll

struct

bytearray