1 using System; 2 namespace HelloWorldApplication 3 { 4 class HelloWorld 5 { 6 static void Main(string[] args) 7 { 8 // 1 9 Console.WriteLine("Hello C# World!"); 10 Console.WriteLine("A:{0}, B:{1}", 10, 20); 11 Console.WriteLine("A:{1}, B:{0}", 10, 20); 12 Console.WriteLine("A:{0}, B:", 10, 20); 13 Console.WriteLine("A:{1}, B:", 10, 20); 14 Console.WriteLine("A:, B:", 10, 20); 15 // 2 16 String str1 = "C:\User"; 17 String str2 = @"C:User"; 18 String str = @" 19 Hello C# World! 20 C# ------ very strong language. 21 "; 22 Console.WriteLine(str1); 23 Console.WriteLine(str2); 24 Console.WriteLine("{1}{0}{1}", str,"/"); 25 //3 26 int val = 123; 27 Object box = val; 28 int valx = (int)box; 29 Console.WriteLine(box); 30 Console.WriteLine(val); 31 Console.WriteLine(valx); 32 //4 33 int a = 9; 34 Object obj; 35 obj = a; 36 obj = 10; 37 Console.WriteLine("a: {0}", a); 38 Console.WriteLine("obj: {0}", obj); 39 //string 40 string xStr = "Hello C#"; 41 Console.WriteLine(xStr); 42 Console.ReadKey(); 43 } 44 } 45 }