using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.IO;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace WindowsFormsApplication2{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private Contact[] phoneBook = new Contact[1];        private void Write(Contact obj)        {                StreamWriter sw = new StreamWriter("contact.txt");                sw.WriteLine(phoneBook.Length + 1);                sw.WriteLine(obj.FirstName);                sw.WriteLine(obj.LastName);                sw.WriteLine(obj.Phone);                for (int x = 0; x < phoneBook.Length; x++)                {                    sw.WriteLine(phoneBook[x].FirstName);                    sw.WriteLine(phoneBook[x].LastName);                    sw.WriteLine(phoneBook[x].Phone);                }                sw.Close();        }        private void Read()        {                            StreamReader sr = new StreamReader("contact.txt");                phoneBook = new Contact[Convert.ToInt32(sr.ReadLine())];                for (int x = 0; x < phoneBook.Length; x++)                {                    phoneBook[x] = new Contact();                    phoneBook[x].FirstName = sr.ReadLine();                    phoneBook[x].LastName = sr.ReadLine();                    phoneBook[x].Phone = sr.ReadLine();                }                sr.Close();        }        private void Display()        {                           lstContacts.Items.Clear();                for (int x = 0; x < phoneBook.Length; x++)                {                    lstContacts.Items.Add(phoneBook[x].ToString());                }                    }        private void ClearForm()        {            textFirstName.Text = string.Empty;            textLastName.Text = string.Empty;            textPhone.Text = string.Empty;        }        private void btnAddContact_Click(object sender, EventArgs e)        {            Contact obj = new Contact();            obj._Contact(textFirstName.Text,textLastName.Text,textPhone.Text);            //lstContacts.Items.Add(obj.ToString());            BubbleSort();            FileIf();            Write(obj);            Read();            Display();            ClearForm();        }        private void FileIf()        {            if (File.Exists("contact.txt"))            {                return;            }else            {                FileStream NewText = File.Create("contact.txt");                NewText.Close();            }        }        private void Form1_Load(object sender, EventArgs e)        {            FileIf();            Read();            Display();        }        private void  BubbleSort()        {            Contact temp;            bool swap;            do            {                swap = false;                for(int x = 0; x<(phoneBook.Length -1);x++)                {                    if (phoneBook[x].LastName.CompareTo(phoneBook[x+1].LastName)>0){                        temp = phoneBook[x];                        phoneBook[x]=phoneBook[x+1];                        phoneBook[x+1]=temp;                        swap =true;                    }                }            }while(swap == true);        }        private void btnSort_Click(object sender, EventArgs e)        {            BubbleSort();            Display();        }           }//end of class}//end of namespace

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace WindowsFormsApplication2{    class Contact    {        //public Contact()        //{        //    FirstName = "landv";        //    LastName = "li";        //    Phone = "13903120312";        //}        //public Contact(string _FirstName, string _LastName, string _Phone)        //{        //    FirstName = _FirstName;        //    LastName = _LastName;        //    Phone = _Phone;        //}               public void  _Contact(string _FirstName, string _LastName, string _Phone)        {            FirstName = _FirstName;            LastName = _LastName;            Phone = _Phone;        }        private string _FirstName;        private string _LastName;        private string _Phone;        public string FirstName        {            get { return _FirstName; }            set { _FirstName = value; }        }        public string LastName        {            get { return _LastName; }            set { _LastName = value; }        }        public string Phone        {            get { return _Phone; }            set             {                if(value.Length == 11)                {                    _Phone = value;                }                else                {                    _Phone = "11111111111";                }            }        }           public override string ToString()       {           string output = string.Empty;           output += string.Format("{0},{1}", LastName, FirstName);           output += string.Format(",{0} {1} {2}", Phone.Substring(0, 3), Phone.Substring(3, 4), Phone.Substring(7, 4));           return output;       }        }// end of class}//end of namespace