《C#高级编程》读书笔记（七）：集合

1，列表的容量和元素个数

    列表的容量和元素个数是两个概念。使用Capacity属性可以获取和设置集合的容量。集合中的元素个数可用用Count属性读取。

    如果列表的容量不足以容纳要添加的元素，就把集合的大小重新设置为原来的2倍。

            var intList = new List<int>();
            intList.Capacity = 20;

            Console.WriteLine(intList.Capacity);//20
            Console.WriteLine(intList.Count);//0

            for (int i = 0; i < 30; i++)
            {
                intList.Add(i);
            }

            Console.WriteLine(intList.Capacity);//40
            Console.WriteLine(intList.Count);//30

 2，向集合中添加元素

            var graham = new Racer(7, "Graham", "Hill", "UK", 14);
            var emerson = new Racer(13, "Emerson", "Fittipaldi", "Brazil", 14);
            var mario = new Racer(16, "Mario", "Andretti", "USA", 12);
            
            //用集合初始化设定项添加
            var racers= new List<Racer>(20) {graham,emerson,mario};

            //显示调用Add()方法来添加
            racers.Add(new Racer(24,"Michale","Schumacher","Germany",91));
            racers.Add(new Racer(27,"Mika","Hakkinen","Finland",20));

            //使用List<T>类的AddRange()方法
            racers.AddRange(new Racer[]
            {
                new Racer(14,"Niki","Lauda","Austria",25),
                new Racer(21,"Alain","Prost","France",51),  
            });

            foreach (var racer in racers)
            {
                Console.WriteLine(racer.ToString());
            }

    List<T>类的ForEach()方法：

//ForEach方法
racers.ForEach(r=>Console.WriteLine($"{r:A}"));

    使用Find方法查找单个元素

racers.Add(new Racer(28,"Shujian","Song","China",90));
            Racer racer1 = racers.Find(r => r.Country == "China");
            Console.WriteLine($"{racer1:A}");

    使用FindAll查询符合条件的集合

            List<Racer> bigWinners = racers.FindAll(r => r.Wins > 20);
            Console.WriteLine("BigWinners:");
            foreach (var bigWinner in bigWinners)
            {
                Console.WriteLine($"{bigWinner:A}");
            }

 3，字典

     用作字典中键的类型必须重写Object类中的GetHashCode()方法。只要字典里需要确定元素的位置，他就要调用GetHashCode()方法。