传递一个结构数组C ++从C＃DLL [英] Passing an struct array into C++ DLL from C#

问题描述

我想通过一个结构数组转换成一个C ++ DLL并运行到的问题。我一直在试图弄明白了数天无果。我可以从C获取数据精细++，我正好碰上问题，当我尝试使用.NET来获取结构数组。

I'm trying to pass a struct array into a C++ DLL and running into issues. I've been trying to figure it out for several days with no avail. I can get the data fine from from C++, I just run into problems when I try to get the struct array using .NET.

C ++的原型是：

static __declspec(dllexport) int SocketAPI::api_get_data(int iSize, buffer_node *data); 

在我的C＃code，我所定义的功能为：

In my C# code, I defined the function as:

[DllImport("SocketAPI.dll")]
static extern int api_get_data(int iSize, buffer_node[] data);

我的结构是其被定义为buffer_node：

My Struct is buffer_node which is defined as:

[StructLayout(LayoutKind.Sequential, Size = 23), Serializable]
public struct header
{
    // HEADER
    public UInt16 h_type; 
    public UInt32 frame_num;  
    public UInt16 count_1pps;   
    public byte data_options;   
    public byte project_type;   
    public byte tile_num;     
    public byte tile_set;          
    public byte total_rows;     
    public byte total_cols;      
    public byte num_rows;         
    public byte num_cols;       
    public byte first_row;        
    public byte first_col;      
    public UInt16 num_sensors;      
    public UInt16 num_data_bytes; 
    public byte h_checksum;
}

[StructLayout(LayoutKind.Sequential, Size = 25), Serializable]
public struct footer
{
    // FOOTER
    public UInt16 f_type;  
    public byte ts_len;           
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 20)]
    public byte[] ts_array;
    public byte frame_status;
    public byte f_checksum;     
}

[StructLayout(LayoutKind.Sequential, Size = 51), Serializable]
public struct buffer_node
{
    // HEADER
    public header data_header;

    // DATA
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
    public byte[] data;

    // FOOTER
    public footer data_footer;
}

如果尝试以下Imports：

If tried the following Imports:

// See buffer, but everything is 0 - ie. not being populated
unsafe static extern int api_get_data(int iSize, buffer_node[] data); 

// fails somewhere in the API
static extern int api_get_data(int iSize, out buffer_node[] data); 

static extern int api_get_data(int iSize, ref buffer_node[] data);

我的C＃的GetData计划目前看起来是这样的：

My C# GetData program currently looks like this:

// Get current data size
int iSize = api_is_data_available();

// Create buffer to hold the data
buffer_node[] buf_data = new buffer_node[iSize];

for (int i = 0; i < iSize; i++)
{
    buf_data[i].data = new byte[3];
    buf_data[i].data_footer.ts_array = new byte[20];
}

// Get the data
//int iStructSize = Marshal.SizeOf(buf_data[0]);
//IntPtr bufNodePtr = IntPtr.Zero;
//IntPtr buffer = Marshal.AllocHGlobal(iStructSize * iSize);
//api_get_data(iSize, buffer);
//for (int i = 0; i < iSize; i++)
//{
//    IntPtr ptr = new IntPtr(buffer.ToInt64() + iStructSize * i);
//    buf_data[i] = (buffer_node)Marshal.PtrToStructure(ptr, typeof(buffer_node));
//}

//api_get_data(iSize, buf_data); // See buffer, but everything is 0 - ie. not being populated
// api_get_data(iSize, out buf_data); // fails no error
api_get_data(iSize, ref buf_data); // fails no error
// api_get_data(iSize, ref buf_data);

// Print the data
for (int i = 0; i < iSize; i++)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Tile Number: " + Convert.ToString(buf_data[i].data_header.tile_num));
    AppendTextBox(sb.ToString());
}

再次感谢您。任何帮助将大大AP preciated，因为我虽然是一个简单的任务是真正扔我一个循环！

Thank you again. Any help would be greatly appreciated, as what I though would be a simple task is really throwing me for a loop!

推荐答案

您必须使用CallingConvention属性的函数[DllImport]属性。默认值是STDCALL，你需要在这里CDECL因为C ++的声明并没有使用__stdcall。

You will have to use the CallingConvention property in the [DllImport] attribute. The default is StdCall, you need Cdecl here since the C++ declaration didn't used __stdcall.

这篇关于传递一个结构数组C ++从C＃DLL的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！