C#之咿呀学语(2)

//goto语句跳出嵌套循环完成数字的查找
int x = 200, y = 4;
            int count = 0;
            string[,] array = new string[x, y];
            for (int i = 0; i < x; i++)
                for (int j = 0; j < y; j++)
                    array[i, j] = (++count).ToString();
            Console.Write("输出结果为：\n输入查找的数字：");
            string myNumber = Console.ReadLine();
            for (int i = 0; i < x; i++)
            {
                for (int j = 0; j < y; j++)
                {
                    if (array[i, j].Equals(myNumber))
                    {
                        goto Found;
                    }
                }
            }
            Console.WriteLine("数字{0}无法找到。",myNumber );
            goto Finish;
        Found:
            Console.WriteLine("数字{0}存在",myNumber );
    Finish:
        Console.WriteLine("结束查找");
        Console.Read();

//通过return语句把CalculateArea()方法的结果值返回给变量area
static double CalculateArea(int r)
        {
            double area = r * r * Math.PI;
            return area;
        }
        static void Main()
        {
            int radius = 4;
            Console.WriteLine("输出结果为：\nThe area is {0:0.00}",CalculateArea (radius));
            Console.Read();
        }

//通过Exception派生了一个新异常类UserEmployeeException，该类定义了3个构造函数，每个构造函数使用不同的参数，然后再抛出自定义异常。
//异常处理语句
        public class UserEmployeeException : Exception
        {
            private string errorinfo = string.Empty;
            public UserEmployeeException(string message)
                : base(message)
            {
                errorinfo = message;
            }
            public UserEmployeeException(string message, Exception inner)
                : base(message, inner)
            {
                errorinfo = message;
                inner = null;
            }
        }
        public static void Main()
        {
            try
            {
                throw new UserEmployeeException("error Info of use");
            }
            catch (UserEmployeeException ey)
            {
                Console.WriteLine("输出结果为：");
                Console.WriteLine(ey.Message,ey.InnerException );
                Console.Read();
            }
        }

//try-catch语句写入多个catch的使用,通过两个catch语句进行捕获异常，他们分别是ArgumentNullException异常和Exception异常
static void ProcessString(string str)
        {
            if (str==null  )
            {
                throw new ArgumentNullException();
            }
        }
        static void Main()
        {
            Console.WriteLine("输出结果是：");
            try
            {
                string str = null;
                ProcessString(str);
            }
            catch (ArgumentNullException e)
            {
                Console.WriteLine("{0} First exception.", e.Message);
            }
            catch (Exception e)
            {
                Console.WriteLine("{0} Second exception",e.Message );
            }
            Console.Read();
        }

//try-catch-finally语句使用
//有一个导致异常的无效转换语句，当运行程序时用户会收到一条运行出错的信息，但finally子句仍继续执行并显示输出。
 static void Main()
        {
            int i = 123;
            string s = "Some string";
            object o = s;
            try
            {
                i = (int)o;
            }
            catch { }
            finally
            {
                Console.WriteLine("输出的结果为：");
                Console.Write("i={0}",i);
            }
            Console.Read();