Console.WriteLine("creating objict myobj...");
            myclass myobj = new myclass("my object");
            Console.WriteLine("myobj created.");
            for (int i = -1; i <= 0; i++)
                try
                {
                    Console.WriteLine("\nattempting to assign {0} to myobj.val...", i);
                    myobj.val = i;
                    Console.WriteLine("ValueType {0} assigned to myobj.val.", myobj.val);
                }
                catch (Exception e)
                {
                    Console.WriteLine("exception {0} thrown.",e.GetType().fullname);
                    Console.WriteLine("message :\n\"{0}\"",e.message);
                }
         }

晕。。。这么简单的还需要讲？多看看书，Console类的用法，循环语句，异常捕获。

这个是C#的最基本的了哟。。。。这是控制台应用程序。主要是一个for循环，try````catch````语句。