//委托  逛超市
        delegate int GuangChaoshi(int a);
        static void Main(string[] args)
        {
            GuangChaoshi gwl = JieZhang;
            Console.WriteLine(gwl(10) + "");   //打印20，委托的應(yīng)用
            Console.ReadKey();
        }
        
        //結(jié)賬
        public static int JieZhang(int a)
        {
            return a + 10;
        }

//委托  逛超市
        delegate int GuangChaoshi(int a);
        static void Main(string[] args)
        {          
           // GuangChaoshi gwl = JieZhang;
            GuangChaoshi 
gwl
 = 
p => p + 10
;
            Console.WriteLine(
gwl(10)
 + "");   //打印20，表達(dá)式的應(yīng)用
            Console.ReadKey();
        }

        //委托  逛超市
        delegate int GuangChaoshi(int a,int b);
        static void Main(string[] args)
        {            
            GuangChaoshi gwl = (p,z) => z-(p + 10);
            Console.WriteLine(gwl(10,100) + "");   //打印80，z對應(yīng)參數(shù)b，p對應(yīng)參數(shù)a
            Console.ReadKey();
        }

    public class Person
    {
        public string Name { get; set; }
        public int Age  {  get;set; }    
    }
    class Program
    {

        public static List<Person> PersonsList()
        {
            List<Person> persons = new List<Person>();
            for (int i = 0; i < 7; i++)
            {
                Person p = new Person() { Name = i + "兒子", Age = 8 - i, };
                persons.Add(p);                
            }
            return persons;
        }

        static void Main(string[] args)
        {
            List<Person> persons = PersonsList();
            persons = persons.Where(p => p.Age > 6).ToList();       //所有Age>6的Person的集合
            Person per = persons.SingleOrDefault(p => p.Age == 1);  //Age=1的單個people類
            persons = persons.Where(p => p.Name.Contains("兒子")).ToList();   //所有Name包含兒子的Person的集合
        }
    }

        static void Main(string[] args)
        {
            Func<int, int, bool> gwl = (p, j) =>
                {
                    if (p + j == 10)
                    {
                        return true;
                    }
                    return false;
                };
            Console.WriteLine(gwl(5,5) + "");   //打印‘True'，z對應(yīng)參數(shù)b，p對應(yīng)參數(shù)a
            Console.ReadKey();
        }

        static void Main(string[] args)
        {
            //i*j+w*x
            ParameterExpression a = Expression.Parameter(typeof(int),"i");   //創(chuàng)建一個表達(dá)式樹中的參數(shù)，作為一個節(jié)點，這里是最下層的節(jié)點
            ParameterExpression b = Expression.Parameter(typeof(int),"j");
            BinaryExpression be = Expression.Multiply(a,b);    //這里i*j,生成表達(dá)式樹中的一個節(jié)點，比上面節(jié)點高一級

            ParameterExpression c = Expression.Parameter(typeof(int), "w");
            ParameterExpression d = Expression.Parameter(typeof(int), "x");
            BinaryExpression be1 = Expression.Multiply(c, d);

            BinaryExpression su = Expression.Add(be,be1);   //運算兩個中級節(jié)點，產(chǎn)生終結(jié)點

            Expression<Func<int, int, int, int, int>> lambda = Expression.Lambda<Func<int, int, int, int, int>>(su,a,b,c,d);

            Console.WriteLine(lambda + "");   //打印‘(i,j,w,x)=>((i*j)+(w*x))'，z對應(yīng)參數(shù)b，p對應(yīng)參數(shù)a

            Func<int, int, int, int, int> f= lambda.Compile();  //將表達(dá)式樹描述的lambda表達(dá)式，編譯為可執(zhí)行代碼，并生成該lambda表達(dá)式的委托；

            Console.WriteLine(f(1, 1, 1, 1) + "");  //打印2
            Console.ReadKey();
        }