Question

C#结构体大小如何计算？结构体中有个数不确定的List

//结构体ScheduleFile
[StructLayout (LayoutKind.Sequential,Pack =1)]
struct ScheduleFile
{
public Int32 schedule_id;
public byte[] basic_schedule_name=new byte [BASIC_SCHEDULE_NAME_LEN];
public Int32 table_count;//服务个数（表个数）
public Table []table_list;//服务列表
}
//结构体Table
[StructLayout(LayoutKind.Sequential,Pack =1)]
struct Table
{
public Int32 table_id;
public Int32 trip_cnt;
public Trip []trip_list;
}
//结构体Trip
[StructLayout(LayoutKind.Sequential,Pack =1)]
struct Trip//单程
{
public byte[] local_sub_id=new byte [LOCAL_SUB_ID_LEN];
public byte[] global_sub_id=new byte [GLOBAL_SUB_ID_LEN];
public ushort trip_flag;
public ushort route_id;
public ushort loop_id;
public byte[] destination_code=new byte [DESTINATION_CODE_LEN];
public ushort record_cnt;
public Record []record_list;
}
//结构体Record
[StructLayout(LayoutKind.Sequential,Pack =1)]
struct Record//记录
{
public ushort station_id;
public ushort platform_id;
public DateTime arrival_time;
public DateTime departure_time;
public Int32 performance_level;
public ushort record_flag;
}
如何计算这样结构体的大小？各列表的个数通过读文件获得

Answer 1

计算这些结构体时，注意以下几点：

1）结构体成员如果类实例、数组，则其在结构体中保存的引用。

• 在32位模式下，每个引用占用4个字节（32位）；

• 在64位模式下，每个引用占用8个字节（64位）
  

2）标准数据类型

• short/ushort：2字节
  

• int/int32/uint：4字节

• DateTime: 8字节

============

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

namespace ConsoleSizeOf
{
        [StructLayout (LayoutKind.Sequential,Pack =1)]
        struct ScheduleFile
        {
            public Int32 schedule_id;
            public byte[] basic_schedule_name;  
            public Int32 table_count;//服务个数（表个数）
            public Table []table_list;//服务列表
            DateTime t;
        }
        //结构体Table
        [StructLayout(LayoutKind.Sequential,Pack =1)]
        struct Table
        {
            public Int32 table_id;
            public Int32 trip_cnt;
            public Trip []trip_list;
        }
        //结构体Trip
        [StructLayout(LayoutKind.Sequential,Pack =1)]
        struct Trip//单程
        {
            public byte[] local_sub_id;
            public byte[] global_sub_id;
            public ushort trip_flag;
            public ushort route_id;
            public ushort loop_id;
            public byte[] destination_code;
            public ushort record_cnt;
            public Record []record_list;
        }
        //结构体Record
        [StructLayout(LayoutKind.Sequential,Pack =1)]
        struct Record//记录
        {
            public ushort station_id;
            public ushort platform_id;
            public DateTime arrival_time;
            public DateTime departure_time;
            public Int32 performance_level;
            public ushort record_flag;
        }

    class Program
    {
        static void Main(string[] args)
        {
            ScheduleFile sf = new ScheduleFile();
            Console.WriteLine("SizeOf(ScheduleFile)={0}", Marshal.SizeOf(sf));
            sf.basic_schedule_name = new byte[100];
            Console.WriteLine("SizeOf(ScheduleFile)={0}, 数组basic_schedule_name已赋值！",
                 Marshal.SizeOf(sf));
            sf.table_list = new Table[100];
            Console.WriteLine("SizeOf(ScheduleFile)={0}, 数组table_list已赋值！", 
                Marshal.SizeOf(sf));

            Table tb = new Table();
            Console.WriteLine("SizeOf(Table)={0}", Marshal.SizeOf(tb));

            Trip tp = new Trip();
            Console.WriteLine("SizeOf(Trip)={0}", Marshal.SizeOf(tp));

            Record rc = new Record();
            Console.WriteLine("SizeOf(Trip)={0}", Marshal.SizeOf(rc));
        }
    }
}

以下结果是在64位系统运行的结果

注意红色方框中的计算结果！