Question

I got a compile error ‘unrecognized escape sequence’ when using \U for unicode literal, is there anything wrong with my program?

  public class TestProject
{

static void Main(string[] args)
{
  string s1 = "\UD800DC09";
  Console.WriteLine(s1);
}
}

Answer 1

See this msdn article. It says: “Unicode characters with code points above 0x10FFFF are not supported.”

EDIT:
May be what you want is:

string s1 = "\uD800\uDC09";