LINQ

CODE:

using System;
using System.Linq;

namespace CsStudy
{
    class Program
    {
        static void Main()
        {
            var gA = new[] { 2, 3, 4, 5 };
            var gB = new[] { 6, 7, 8, 9 };

            var some = from a in gA
                       from b in gB
                       let sum = a + b
                       where a >= 4 && b <= 8
                       where sum > 11
                       orderby b
                       group sum by sum;//分组键sum
            var some2 = from a in gA
                        from b in gB
                        where a + b < 11
                        select new { a, b, sum = a + b };//匿名类型对象

            foreach (var a in some2)
                Console.WriteLine(a);
            foreach (var b in some)
                Console.WriteLine(b.Key);

            var cOdd = gB.Count(n => n % 2 == 1);//lambda表达式 +扩展方法
            Console.WriteLine(cOdd);

            Console.ReadKey();
        }
    }
}

输出:

{ a = 2, b = 6, sum = 8 }
{ a = 2, b = 7, sum = 9 }
{ a = 2, b = 8, sum = 10 }
{ a = 3, b = 6, sum = 9 }
{ a = 3, b = 7, sum = 10 }
{ a = 4, b = 6, sum = 10 }
12
13
2