C#查询表达式

程序使用vs 2010编写

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace demo33
{
    public partial class Form1 : Form
    {
        int[] numbers = new int[7] { 0, 31, 12, 6, 34, 51, 6 };
        public Form1()
        {
            InitializeComponent();
            for (int i = 0; i < numbers.Length; i++)
            {
                listBox1.Items.Add(numbers[i].ToString());
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            //创建查询
            var result0 =
                from num in numbers
                where (num % 2) == 0
                select (num.ToString());
            foreach (string num in result0)
            {
                listBox1.Items.Add(num);
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            var result3 =
                from num in numbers
                where num > 2
                orderby num descending//从大到小排序
                select num;
            foreach (int num in result3)
            {
                listBox1.Items.Add(num);
            }
        }
        private void button4_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            var result3 =
                from num in numbers
                where num > 2
                orderby num ascending //按照ascending方式排序从最小到最大的排序顺序。
                //select string.Format("当前项的值为{0}",num)
                select num;
            foreach (int num in result3)
            {
                listBox1.Items.Add(num);
            }

        }

        private void button5_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            int[] numbers = new int[7] { 0, 31, 12, 6, 34, 51, 6 };
            int result3 = 0;
            switch (comboBox1.Text)
            {
                case "Max":
                    result3 =
                (from num in numbers
                 where num > 2
                 select num).Max(); break;
                case "Min":
                    result3 =
               (from num in numbers
                where num > 2
                select num).Min(); break;
                case "Count":
                    result3 =
                  (from num in numbers
                   select num).Count(); break;
                default: MessageBox.Show("功能未完善"); break;

            }
            listBox1.Items.Add(result3);
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }
    }
}