PraktikaGlava4/Form1.cs

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 Praktika409
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            AutoCompleteStringCollection source = new AutoCompleteStringCollection()
        {
            "Кузнецов",
            "Иванов",
            "Петров",
            "Кустов"
        };
            textBox1.AutoCompleteCustomSource = source;
            textBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;
            textBox3.TextChanged += textBox3_TextChanged;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Hello World");
        }

        private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
        {
            System.Diagnostics.Process.Start("http://metanit.com");
        }

        private void textBox4_TextChanged(object sender, EventArgs e)
        {
            
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
            label3.Text = textBox3.Text;
        }
    }
}