C# program to find all duplicate elements in an integer array

Firstly, set the array with duplicate elements.

int[] arr = {
   24,
   10,
   56,
   32,
   10,
   43,
   88,
   32
};

Now declare a Dictionary and loop through the array to get the repeated elements.

var d = new Dictionary < int, int > ();
foreach(var res in arr) {
   if (d.ContainsKey(res))
         d[res]++;
   else
   d[res] = 1;
}

Example

 Live Demo

using System;
using System.Collections.Generic;

namespace Demo {
   public class Program {
      public static void Main(string[] args) {
         int[] arr = {
            24,
            10,
            56,
            32,
            10,
            43,
            88,
            32
         };
         var d = new Dictionary < int, int > ();
         foreach(var res in arr) {
            if (d.ContainsKey(res))
            d[res]++;
            else
            d[res] = 1;
         }
         foreach(var val in d)
         Console.WriteLine("{0} occurred {1} times", val.Key, val.Value);
      }
   }
}

Output

24 occurred 1 times
10 occurred 2 times
56 occurred 1 times
32 occurred 2 times
43 occurred 1 times
88 occurred 1 times