关于自动属性和对象初始化器

当初始化类的对象时，如果有多个属性，考虑到每一种组合的话需要定义很多构造器，显然这是很麻烦的，通过对象初始化器可以很好地解决这个问题

1. 在类中对字段初始化；
2. 创建对象的时候使用对象初始化器；

//在创建类的时候对其属性进行初始化
class Polygon
    {
        public int NumSides { get; set; }
        public double SideLength { get; set; }
        public Polygon()
        {
            this.NumSides = 4;
            this.SideLength = 10.0;
        }
}
//在创建对象时使用对象初始化器
static void DoWork()
        {
            // to do
            Polygon square = new Polygon();
            Polygon triangle = new Polygon { NumSides = 3 };
            Polygon pentagon = new Polygon { SideLength = 15.5, NumSides = 5 };
            Console.WriteLine("Square: number of sides is {0},length of each side is {1}",square.NumSides,square.SideLength);
            Console.WriteLine("triangle: number of sides is {0},length of each side is {1}", triangle.NumSides, triangle.SideLength);
            Console.WriteLine("pentagon: number of sides is {0},length of each side is {1}", pentagon.NumSides, pentagon.SideLength);
        }

        static void Main(string[] args)
        {
            try
            {
                DoWork();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }