20180309 - C# demo - 1

 using System;
 namespace HelloWorldApplication
 {
     class HelloWorld
     {
         static void Main(string[] args)
         {
             //
             Console.WriteLine("Hello C# World!");
             Console.WriteLine("A:{0}, B:{1}", , );
             Console.WriteLine("A:{1}, B:{0}", , );
             Console.WriteLine("A:{0}, B:", , );
             Console.WriteLine("A:{1}, B:", , );
             Console.WriteLine("A:, B:", , );
             //
             String str1 = "C:\\User";
             String str2 = @"C:\User";
             String str = @"
             Hello C# World!
     C# ------        very strong language.
             ";
             Console.WriteLine(str1);
             Console.WriteLine(str2);
             Console.WriteLine("{1}{0}{1}", str,"/");
             //
             int val = ;
             Object box = val;
             int valx = (int)box;
             Console.WriteLine(box);
             Console.WriteLine(val);
             Console.WriteLine(valx);
             //
             int a = ;
             Object obj;
             obj = a;
             obj = ;
             Console.WriteLine("a: {0}", a);
             Console.WriteLine("obj: {0}", obj);
             //string
             string xStr = "Hello C#";
             Console.WriteLine(xStr);
             Console.ReadKey();
         }
     }
 }