在托管C＃中声明结构数组的问题？ [英] Problem in declaring the array of structures in managed C#?

问题描述

我不知道以前有人问同样的问题。当我试图在网上搜索时，我找不到它。请帮我解决这个问题？

 使用系统; 
 使用 System.Collections.Generic; 
 使用 System.Linq; 
 使用 System.Runtime.InteropServices; 
 使用 System.Text; 
 使用 System.Threading.Tasks; 
 
 命名空间 ConsoleApplication1 
 {
  class 计划
 {
 [StructLayout（LayoutKind.Sequential）] 
  public   class 详情
 {
  public   uint  ID; 
  public   uint  state; 
  public   uint  country; 
  public   uint  place; 
} 
 [StructLayout（LayoutKind.Sequential）] 
  public   class  UserDetails 
 {
 [MarshalAs（UnmanagedType.ByValArray，SizeConst =  8 ）] 
  public  Details [] userDetails; 
} 
 静态  void  Main（ string  [] args）
 {
 
 UserDetails u =  new  UserDetails（）; 
  int  sizeofDetails = Marshal.SizeOf（u）; 
} 
} 
} 

当我执行代码时，我期待sizeofDetails应该是128.但我得到64.



声明数组是否有任何问题。有人可以帮忙吗？

解决方案

为什么你期望它是128字节？详细信息是类，而不是 struct ，因此Details元素数组将是对元素的引用数组，不是元素本身。

因为你使用64位系统，每个引用是8个字节，所以每个数组是8 * 8字节== 64字节。



您可能会尝试将详细信息设为 struct ：然后它是一个值类型，数组将直接包含元素而不是元素的引用。

I dont know if previously someone asked the same. When i tried to search in the net, i couldn't find it. Please help me in solving this?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
            [StructLayout(LayoutKind.Sequential)]
        public class Details
        {
            public uint ID;
            public uint state;
            public uint country;
            public uint place;
        }
        [StructLayout(LayoutKind.Sequential)]
        public class UserDetails
        {
            [MarshalAs(UnmanagedType.ByValArray, SizeConst=8)]
            public Details[] userDetails;
        }
        static void Main(string[] args)
        {

            UserDetails u = new UserDetails();
            int sizeofDetails = Marshal.SizeOf(u);
        }
    }
}

When i executed the code, i am expecting the sizeofDetails should be 128. But i am getting 64.

Is there any problem in declaration of the array. Can someone please help?

解决方案

Why would you expect it to be 128 bytes? Details is a class, not a struct so an array of Details elements will be an array of references to the elements, not the elements themselves.
Since you are using a 64 bit system, each reference is 8 bytes, and so each array is 8 * 8 bytes == 64 bytes.

You might try making Details a struct instead: then it's a value type and the array will directly contain the elements instead of references to the elements.

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