习题

习题.jpg

练习1

- 代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            //定义数组
            var human = new[]
            {
                new{name="李药师",age=62,sex="male"},
                new{name="王铁柱",age=57,sex="female"},
                new{name="巢昱清",age=57,sex="female"},
                new{name="倪丹映",age=61,sex="female"},
            };

            //创建查询
            var query = from s in human
                        where s.age >= 60
                        select s;

            //执行查询
            foreach (var val in query)
            {
                Console.WriteLine($"{val}");
            }
        }
    }
}

- 运行结果

AfterRun.PNG

练习2

- 代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            //定义数组
            int[] num = { 23, 45, 56, 77, 23, 45, 98, 12, 4, 9 };

            //创建查询1
            var query1 = from val in num
                         orderby val ascending
                         select val;
            Console.WriteLine("升序数组");

            //执行查询后
            foreach(var item in query1)
            {
                Console.Write($"{item} ");
            }
            Console.WriteLine();

            //创建查询2
            var query2 = from val in num
                         orderby val descending
                         select val;
            Console.WriteLine("降序数组");
            //执行查询后
            foreach (var item in query2)
            {
                Console.Write($"{item} ");
            }
            Console.WriteLine();
        }
    }
}

- 运行结果

AfterRun.PNG

练习3

- 代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp3
{
    class Program
    {
        static void Main(string[] args)
        {
            //定义数组
            var customer = new[]
            {
                new{name="李药师",age=25,sex="male",city="北京"},
                new{name="巢昱清",age=19,sex="female",city="上海"},
                new{name="王铁柱",age=19,sex="female",city="北京"},
                new{name="张德培",age=23,sex="male",city="江苏"},
                new{name="蔡文炫",age=25,sex="female",city="上海"},
                new{name="单中华",age=28,sex="male",city="江苏"},
                new{name="刘慧群",age=25,sex="female",city="江西"},
            };

            //创建查询
            var query = from s in customer
                        //使用城市分组
                        group s by s.city;

            //执行查询
            foreach (var grp in query)
            {
                Console.WriteLine($"{grp.Key}");
                foreach (var item in grp)
                {
                    Console.WriteLine($"{item}");
                }
                Console.WriteLine();
            }
        }
    }
}

- 运行结果

AfterRun.PNG

练习4

自己抄书