我有以下 C 头文件/代码示例:
头文件
struct category_info {
int id;
const char *name;
const char *description;
};
DLLEXPORT
void* xyz_categories_info(struct category_info **info, size_t *info_count);
示例 C 代码段
struct category_info *catinfo;
size_t catcount;
size_t i;
int max_name_len = 0;
void *catmem = xyz_categories_info(&catinfo, &catcount)
我想将其转换为 C#...
我的第一个猜测(也是一个猜测)是:
[StructLayout(LayoutKind.Sequential)]
public struct category_info
{
int id;
[MarshalAs(UnmanagedType.LPStr)]
StringBuilder name;
[MarshalAs(UnmanagedType.LPStr)]
StringBuilder description;
};
[DllImport("mydll.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
public static extern IntPtr xyz_categories_info([Out]category_info cat, [Out]int catSize);
但它看起来不对..
任何建议.. 一旦在 C# 中正确声明了上述内容.. 应该如何在 C# 中访问它
category_info catinfo;
catmem = xyz_categories_info(out catinfo, out catcount);
??????
非常感谢任何帮助。
谢谢
============================================= =================================
更新2
xyz_categories_info 中分配的内存使用此 C 调用释放:
void xyz_categories_info_free(void *p);
下面是一个在 C 中使用它的例子....希望这能解释得更多一点..
category_buffer = xyz_categories_info(&category_info, &category_count);
if( !category_buffer )
{
// Failed Log a message and exit.
exit(1);
}
for(j=0; j<category_count; j++)
{
if( category_info[j].id == 0 )
continue;
printf("id: %d name: '%s' description: '%s'\n",
category_info[j].id,
category_info[j].name,
category_info[j].description
);
}
xyz_categories_info_free(category_buffer);
最佳答案
此代码已编译,但未经过测试。如果您了解 C,就会明白这里发生了什么,这只是将相同的 C 代码转换为 C#。
using System; using System.Collections.Generic; using System.Text; using System.Runtime.InteropServices; namespace ConsoleApplication1 { public struct category_info { public int id; public IntPtr name; public IntPtr description; }; class Program { [DllImport("mydll.dll", CallingConvention = CallingConvention.Cdecl)] public static extern IntPtr xyz_categories_info(ref IntPtr cat, ref int catSize); [DllImport("mydll.dll", CallingConvention = CallingConvention.Cdecl)] public static extern void xyz_categories_info_free(IntPtr cat); static void Main(string[] args) { IntPtr categories = IntPtr.Zero; IntPtr category_buffer = IntPtr.Zero; int category_count = 0; category_info info = new category_info(); IntPtr current; try { category_buffer = xyz_categories_info(ref categories, ref category_count); if (category_buffer == IntPtr.Zero) { return; } if (category_count == 0) { return; } for (int j = 0; j < category_count; j++) { if (IntPtr.Size == 4) { current = new IntPtr(categories.ToInt32() + j * Marshal.SizeOf(info)); } else { current = new IntPtr(categories.ToInt64() + j * Marshal.SizeOf(info)); } info = (category_info)Marshal.PtrToStructure(current, typeof(category_info)); if (info.id == 0) { continue; } Console.WriteLine(info.id); Console.WriteLine(Marshal.PtrToStringAnsi(info.name)); Console.WriteLine(Marshal.PtrToStringAnsi(info.description)); } } finally { if (category_buffer != IntPtr.Zero) { xyz_categories_info_free(category_buffer); } } } } }
关于用于 C 结构和函数的 C# 编码,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4204019/