Eliminates duplicate values from combo box

Question

This is the actual code   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 WindowsFormsApp1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void timer1_Tick(object sender, EventArgs e) { comboBox1.Items.Add("Duplicate"); } private void comboBox1_SelectedIndexChanged(object sender, EventArgs e) { } private void Form1_Load(object sender, EventArgs e) { comboBox1.Items.RemoveAt(); timer1.Start(); } } }     can someone help me?

Rajanikant Hawaldar · Accepted Answer

Hey Jhaz, changed code check you was not checking combobox contains items before adding in timer tick event. 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  WindowsFormsApp1   {   public  partial  class  Form1 : Form   {   public  Form1()   {   InitializeComponent();   }   private   void  timer1_Tick( object  sender, EventArgs e)   {         if (!comboBox1.Items.Contains( "Duplicate" ))        {             comboBox1.Items.Add( "Duplicate" );        }   }   private   void  comboBox1_SelectedIndexChanged( object  sender, EventArgs e)   {   }   private   void  Form1_Load( object  sender, EventArgs e)   {   comboBox1.Items.RemoveAt();   timer1.Start();   }   }   }

Sachin Singh · Answer

If you have already added duplicate values in combox and now want to remove them then following code is what you need var itemArry= ComboBox1.Items.SelectMany(i => i).Distinct().ToArray();   ComboBox1.Items.Clear();   ComboBox1.Items.AddRange(itemArry);
If you want to prevent duplicate entries then follow   if (!comboBox1.Items.Contains( "Duplicate" ))          {               comboBox1.Items.Add( "Duplicate" );          }