C#

using System;
using System.Text;
 
class HtmlEntities
{
  static void Main(string[] args)
  {
    if (args.Length > 0)
    {
      Console.WriteLine(HtmlFormat(args[0]));
    }
  }
 
  static string HtmlFormat(string value)
  {
    StringBuilder sb = new StringBuilder(value.Length * 7);
    Encoding enc = Encoding.Unicode;
 
    foreach (char c in value)
    {
      byte[] buffer = enc.GetBytes(new char[] {c});
      int i = BitConverter.ToInt16(buffer, 0);
      sb.Append("&#" + i.ToString() + ";");
    }
 
    return sb.ToString();
  }
}