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 LinqTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int[] numbers = new int[7] { 0, 1, 2, 3, 4, 5, 6 };
            //創(chuàng)建查詢
            //查詢結(jié)果的類型是IEnumberable<int>
            var result0 = from num in numbers 
                         where (num % 2) == 0 
                         select num;
            //執(zhí)行查詢結(jié)果
            foreach (int num in result0)
            {
                listBox1.Items.Add(num);
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            int[] numbers = new int[7] { 2, 1, 2, 6, 4, 5, 3 };
            var result1 =                       //聲明查詢
                          from num in numbers   //聲明臨時(shí)變量num，其值來源于numbers
                          where num>3           //當(dāng)前值大于3
                          orderby num descending//按照descending方式排序,，降序
                          select num;           //將當(dāng)前項(xiàng)加入到結(jié)果序列中
            foreach (int num in result1)
            {
                listBox1.Items.Add(num);
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            int[] numbers = new int[7] { 2, 1, 2, 6, 4, 5, 3 };
            var result2 =                       //聲明查詢
                          from num in numbers   //聲明臨時(shí)變量num,，其值來源于numbers
                          where num > 3           //當(dāng)前值大于3
                          orderby num ascending//按照ascending方式排序，升序
                          select string.Format("當(dāng)前項(xiàng)值為{0}",num);           //將當(dāng)前項(xiàng)加入到結(jié)果序列中
            foreach (string num in result2)
            {
                listBox1.Items.Add(num);
            }
        }

        private void button4_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            int[] numbers = new int[7] { 2, 1, 2, 6, 4, 5, 3 };
            int result3 =                       //聲明查詢
                          (from num in numbers   //聲明臨時(shí)變量num,，其值來源于numbers
                          where num > 3           //當(dāng)前值大于3
                          select num).Count();           //將當(dāng)前項(xiàng)加入到結(jié)果序列中  
            button4.Text += "--" + result3.ToString();
        }
    }
}