marshal:直译为“编排”， 在计算机中特 指将数据按某种描述格式编排出来，通常来说一般是从非文本格式到文本格式的数据转化。
unmarshal是指marshal的逆过程。比如在WebService中，我们需要把java对象以xml方式表示并在网络间传输，把java对象转化成xml片段的过程就是marshal.
微软对C#中Marshal类描述的链接在此；
https://docs.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.marshal?view=net-5.0
Provides a collection of methods for allocating unmanaged memory, copying unmanaged memory blocks, and converting managed to unmanaged types, as well as other miscellaneous methods used when interacting with unmanaged code.
提供一个方法集合，分配非托管内存，拷贝非托管内存块，转换托管和非托管类型，以及一些和非托管代码交互的杂类方法；
这是Marshal类的基本功能；.net一共包含四个Marshal类，每个都有一些方法；
下面来看一个Marshal类基本程序；程序运行结果如下；
代码如下；
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace marshalDemo1
{
public struct Point
{
public Int32 x, y;
}
public partial class Form1 : Form
{
[DllImport("Kernel32", ExactSpelling = true, SetLastError = true)]
static extern Boolean CloseHandle(IntPtr h);
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
textBox1.Text = Marshal.SystemDefaultCharSize.ToString();
textBox2.Text = Marshal.SystemMaxDBCSCharSize.ToString();
textBox3.Text = Marshal.SizeOf(typeof(Point)).ToString();
Point p = new Point();
textBox4.Text = Marshal.SizeOf(p).ToString();
IntPtr hglobal = Marshal.AllocHGlobal(100);
textBox5.Text = hglobal.ToString();
Marshal.FreeHGlobal(hglobal);
Boolean f = CloseHandle(new IntPtr(-1));
if (!f)
{
Console.WriteLine("CloseHandle call failed with an error code of: {0}",
Marshal.GetLastWin32Error());
}
}
}
}