C#实现 javascript中的 charCodeAt

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace ConsoleApp1
{
    internal class Program
    {
        static void Main(string[] args)
        {
            string n= "中国".charCodeAt(1);            
            Console.WriteLine(n);
 
            n = "中华人民共和国".charCodeAt();
            Console.WriteLine(n);
 
        }
        
    }
    public static class A
    {
        public static string charCodeAt(this string character,int index)
        {            
            return (character[index]+"").charCodeAt();
        }
            public static string charCodeAt(this string character)
        {
 
            string coding = "";
            for (int i = 0; i < character.Length; i++)
            {
                byte[] bytes = System.Text.Encoding.Unicode.GetBytes(character.Substring(i, 1));
 
                //取出二进制编码内容  
                string lowCode = System.Convert.ToString(bytes[1], 16);
 
                //取出低字节编码内容（两位16进制）  
                if (lowCode.Length == 1)
                {
                    lowCode = "0" + lowCode;
                }
 
                string hightCode = System.Convert.ToString(bytes[0], 16);
 
                //取出高字节编码内容（两位16进制）  
                if (hightCode.Length == 1)
                {
                    hightCode = "0" + hightCode;
                }
 
                coding += (hightCode + lowCode);
 
            }
 
            return coding; 
        }
    }
}