请问这几行代码的意思是什么？
private static string DecodeTime(string timeStr)
  {
  char[] timeArr = timeStr.ToCharArray();
  timeArr[0] = (char)(timeArr[0] - '\x0002');
  timeArr[1] = (char)(timeArr[1] - '\x0006');
  timeArr[2] = (char)(timeArr[2] - '\x0004');
  timeArr[3] = timeArr[3];
  timeArr[4] = (char)(timeArr[4] - '\x0005');
  timeArr[5] = timeArr[5];
  timeArr[6] = (char)(timeArr[6] - '\x0003');
  timeArr[7] = timeArr[7];
   
  }

我在调试中把20090728 传入，得出的timeArr为 0*,9+7/8 为什么会这样

------解决方案--------------------
20090728在经过

C# code

char[] timeArr = timeStr.ToCharArray(); 
变成char[] {'2','0','0','9',...}