LinQ trong lập trình C# Winform

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

namespace LinQGUI
{
    public partial class Form1 : Form
    {
        List<Food> foodList;
        public Form1()
        {
            InitializeComponent();
            LoadFood();
        }

        void LoadFood()
        {
            foodList = new List<Food>();
            foodList.Add(new Food("Dú dê nướng", "55555"));
            foodList.Add(new Food("Mực một nắng nướng muối ớt", "999999"));
            foodList.Add(new Food("Ếch núp nùm", "333333"));
            foodList.Add(new Food("cái gì đây", "1"));
            foodList.Add(new Food("7up", "15000"));
            foodList.Add(new Food("Ốc mỡ cháy tỏi", "50000"));

            cbData.DataSource = foodList;
            cbData.DisplayMember = "Name";
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            List<Food> result = new List<Food>();

            //foreach (Food item in foodList)
            //{
            //    if (item.Name == txbKey.Text)
            //    {
            //        result.Add(item);
            //    }
            //}

            //result = foodList.Where(p => p.Name == txbKey.Text).ToList();
            //var result2 = foodList.Select(p=>p.Price).SingleOrDefault();

            //result = foodList.Skip(2).Take(2).ToList();
            result = foodList.OrderBy(p=>Convert.ToInt32(p.Price)).ToList();

            cbResult.DataSource = result;
            cbResult.DisplayMember = "Name";
        }
    }

    public class Food
    {
        private string price;

        public string Price
        {
            get { return price; }
            set { price = value; }
        }
        private string name;

        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        public Food() { }

        public Food(string name, string price) 
        {
            this.Name = name;
            this.Price = price;
        }
    }
}
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namespace LinQGUI
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.cbData = new System.Windows.Forms.ComboBox();
            this.btnSearch = new System.Windows.Forms.Button();
            this.txbKey = new System.Windows.Forms.TextBox();
            this.cbResult = new System.Windows.Forms.ComboBox();
            this.SuspendLayout();
            // 
            // cbData
            // 
            this.cbData.DropDownStyle = System.Windows.Forms.ComboBoxStyle.Simple;
            this.cbData.FormattingEnabled = true;
            this.cbData.Location = new System.Drawing.Point(12, 46);
            this.cbData.Name = "cbData";
            this.cbData.Size = new System.Drawing.Size(134, 215);
            this.cbData.TabIndex = 0;
            // 
            // btnSearch
            // 
            this.btnSearch.Location = new System.Drawing.Point(118, 10);
            this.btnSearch.Name = "btnSearch";
            this.btnSearch.Size = new System.Drawing.Size(75, 23);
            this.btnSearch.TabIndex = 1;
            this.btnSearch.Text = "Filter";
            this.btnSearch.UseVisualStyleBackColor = true;
            this.btnSearch.Click += new System.EventHandler(this.btnSearch_Click);
            // 
            // txbKey
            // 
            this.txbKey.Location = new System.Drawing.Point(12, 12);
            this.txbKey.Name = "txbKey";
            this.txbKey.Size = new System.Drawing.Size(100, 20);
            this.txbKey.TabIndex = 2;
            // 
            // cbResult
            // 
            this.cbResult.DropDownStyle = System.Windows.Forms.ComboBoxStyle.Simple;
            this.cbResult.FormattingEnabled = true;
            this.cbResult.Location = new System.Drawing.Point(152, 46);
            this.cbResult.Name = "cbResult";
            this.cbResult.Size = new System.Drawing.Size(120, 215);
            this.cbResult.TabIndex = 3;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(284, 261);
            this.Controls.Add(this.cbResult);
            this.Controls.Add(this.txbKey);
            this.Controls.Add(this.btnSearch);
            this.Controls.Add(this.cbData);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.ComboBox cbData;
        private System.Windows.Forms.Button btnSearch;
        private System.Windows.Forms.TextBox txbKey;
        private System.Windows.Forms.ComboBox cbResult;
    }
}

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