C# Online Compiler | .NET Fiddle

using System;
					
public class Program
{
	public static void Main()
	{
var s4 = 
new String(
new char[]{'w', 'o', 'r', 'l', 'd'});
//	s4[1] = 'd'; error - string.this[int] is read only
//https://unicode-table.com/
Console.WriteLine("\u2642 \U0001F47D \x2640");
long number1 = 19876543210;
Console.WriteLine(
number1.ToString("+# (###) ###-##-##"));
Console.WriteLine(
$"{number1:C}"); 
Console.WriteLine(
string.Format("number1={0:X}",19876543210));	
	}
}

 
using System;
                    
public class Program
{
    public static void Main()
    {
var s4 = 
new String(
new char[]{'w', 'o', 'r', 'l', 'd'});
//  s4[1] = 'd'; error - string.this[int] is read only
//https://unicode-table.com/
Console.WriteLine("\u2642 \U0001F47D \x2640");
long number1 = 19876543210;
Console.WriteLine(
number1.ToString("+# (###) ###-##-##"));
Console.WriteLine(
$"{number1:C}"); 
Console.WriteLine(
string.Format("number1={0:X}",19876543210));    
    }
}