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 _04TextBox

{

    public partial class Form1 : Form

    {

        List<string> Data = new List<string>();

        string Randomstr = "功夫撒黑胡椒hcbvf蜂窝qwertyuiopasdfghjklzxcvbnm法国的恢复到飞范德萨QWERTYUIOPASDFGHJKLZXCVBNM出现过热423贴①46546也有一头热刚恢复到贴3天赋如头3广泛的我让他";

        Random rd = new Random(GetRandomSeed());

        static int GetRandomSeed()

        {

            byte[] bytes = new byte[];

            System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();

            rng.GetBytes(bytes);

            return BitConverter.ToInt32(bytes, );

        }

        public Form1()

        {

            InitializeComponent();

            //2000W数据，这里会有卡顿现象，这里修改为200W

            for (int i = ; i < ; i++)

            {

                Data.Add(Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()

                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()

                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()

                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()

                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString());

            }

            //重点代码

            this.textBox1.AutoCompleteCustomSource.Clear();

            this.textBox1.AutoCompleteCustomSource.AddRange(Data.ToArray());

            this.textBox1.AutoCompleteMode = System.Windows.Forms.AutoCompleteMode.SuggestAppend;

            this.textBox1.AutoCompleteSource = System.Windows.Forms.AutoCompleteSource.CustomSource;

        }

        private void Form1_Load(object sender, EventArgs e)

        {

        }

    }

}

#region 实现提示文字

        Boolean textboxHasText = false;//判断输入框是否有文本

        /// <summary>

        /// textbox获得焦点

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void textBox1_Enter(object sender, EventArgs e)

        {

            if (textboxHasText == false)

                textBox1.Text = "";

            textBox1.ForeColor = Color.Black;

        }

        /// <summary>

        /// textbox失去焦点

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void textBox1_Leave(object sender, EventArgs e)

        {

            if (textBox1.Text == "")

            {

                textBox1.Text = "提示内容";

                textBox1.ForeColor = Color.LightGray;

                textboxHasText = false;

            }

            else

                textboxHasText = true;

        }

        #endregion