如何通过.NET判断文件是否已更改？

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string filePath = "example.txt";
        DateTime lastModifiedTime = File.GetLastWriteTime(filePath);

        Console.WriteLine("Last modified time: " + lastModifiedTime);

        // 在这里执行一些操作，例如修改文件
        // ...

        DateTime newLastModifiedTime = File.GetLastWriteTime(filePath);

        if (newLastModifiedTime > lastModifiedTime)
        {
            Console.WriteLine("The file has been modified.");
        }
        else
        {
            Console.WriteLine("The file has not been modified.");
        }
    }
}