How to remove a duplicate number from an array?

Question

Hi I'm working on this simple program that takes 5 numbers from user as long as the numbers are greater than 10 and less than 100. My goal is to remove duplicates numbers an ONLY show the NOT DUPLICATE numbers. Let's say if I enter 23 , 23, 40, 56 , 37 I should only output 40 , 56 , 37. Please help me on this. Thanks in advance. Here's my code:

    static void Main(string[] args)
    {
        int[] arr = new int[5];  
        for (int i = 0; i < 5; i++)
        {
            Console.Write("\nPlease enter a number between 10 and 100: ");
            int number = Convert.ToInt32(Console.ReadLine());
            if (number > 10 && number <= 100)
            {
                arr[i] = number;
            }
            else {
                i--;
            }

        }

        int[] arr2 = arr.Distinct().ToArray(); 
        Console.WriteLine("\n");
        for (int i = 0; i < arr2.Length; i++)
        {
            Console.WriteLine("you entered {0}", arr2[i]);
        }
        Console.ReadLine();
    }

possible duplicate of [this](http://stackoverflow.com/questions/9673/remove-duplicates-from-array) — Debosmit Ray, Mar 02 '16 at 04:10
@Ian I think he dont want to show the duplicate values in the list.. Distinct will include it once — Olivarsham, Mar 02 '16 at 04:12
@Olivarsham YES I dont want to show duplicate values. As you can see I'm already using Distinct() , but I dont want to show duplicate values. Any ideas how to fix that? — , Mar 02 '16 at 04:14
You can surely bend LINQ to solve this problem. But given that this is clearly a beginning programmer's exercise, you would be much better served by writing the algorithm yourself. As stated, the question is too broad; even limiting solutions to LINQ, there are many possible solutions. Please show an attempt to solve the problem, explaining precisely what you are having trouble with — Peter Duniho, Mar 02 '16 at 04:17
Here your code has no problems. Take a look: http://ideone.com/8mkjb5 — developer033, Mar 02 '16 at 04:25

score 4 · Answer 1 · answered Mar 02 '16 at 04:15

4

One way is to group the elements based on input number and filter groups whose count is 1

int[] arr2 = arr.GroupBy(e=>e)                  
                .Where(e=>e.Count() ==1)
                .Select(e=>e.Key).ToArray();

Demo

answered Mar 02 '16 at 04:15

Hari Prasad

16,716
4
21
35

sujith karivelil · Accepted Answer · 2016-03-02T04:55:49.160

I think you are looking for this:

 int[] arr2 = arr.GroupBy(x => x)
              .Where(dup=>dup.Count()==1)
              .Select(res=>res.Key)
              .ToArray();

Input Array : 23 , 23, 40, 56 , 37 Output Array : 40 , 56 , 37

How it Works:

arr.GroupBy(x => x) => give a collection of {System.Linq.GroupedEnumerable<int,int,int>} where x.Key gives you the unique elements.
.Where(dup=>dup.Count()==1)=> Extracts the the KeyValuePairs that contains Values count exactly equal to 1
.Select(res=>res.Key) => will collects the Keys from the above result

score 1 · Answer 3 · answered Mar 02 '16 at 04:15

1

In your case, perhaps a combination of LINQ methods would be needed:

int[] arr2;
int[] nodupe = arr2.GroupBy(x => x).Where(y => y.Count() < 2).Select(z => z.Key).ToArray();

answered Mar 02 '16 at 04:15

Ian

30,182
19
69
107

How to remove a duplicate number from an array?

3 Answers3