Deleting duplicates in an array

Question

Here is the code. It's just deleting the half of duplicate elements from an array and others are to remain there. don't know what is the problem. need assistance thank you.

 int[] count_list = { 10, 20, 10, 30, 30, 40, 20, 50, 90, 60, 80, 70, 80, 90 };
 int l = count_list.Length;   
 for (int i = 0; i < l; i++)
 {
      for (int j =i + 1; j < l;)
      {
           if(count_list[j] == count_list[i]){
                for (int k = j; k < l; k++)
                {
                     count_list[k] = count_list[k + 1] ;
                     l--;
                }

           }
           else{
                j++;
           }
      }       
 }

 for (int i = 0; i < count_list.Length; i++)
 {
      Console.WriteLine(count_list[i]);
      //  Console.WriteLine("name");
 }

possible duplicate of [Delete Duplicate from an Array](http://stackoverflow.com/questions/2055668/delete-duplicate-from-an-array) — atoMerz, Feb 11 '14 at 23:11

p.s.w.g · Accepted Answer · 2014-02-11T23:17:44.247

The problem is that you're decrementing l with each iteration inner-most for-loop. Try rewriting it like this:

for (int i = 0; i < l; i++)
{
    for (int j = i + 1; j < l;)
    {
        if(count_list[j] == count_list[i]){
            l--;
            for (int k = j; k < l; k++)
            {
                count_list[k] = count_list[k + 1] ;
            }
            break;
        }
        else{
            j++;
        }
    }
}

And remember to call Resize if you want to shrink the array back down at the end:

Array.Resize(ref count_list, l);

However, this is a lot of unnecessary work. I'd strongly suggest using a HashSet<T> or Linq's Distinct extension method:

count_list = count_list.Distinct().ToArray();

score 0 · Answer 2 · answered Feb 11 '14 at 23:11

0

You can just use the Distinct method to produce a new array without duplicates;

int[] noDupes = count_list.Distinct().ToArray();

answered Feb 11 '14 at 23:11

evanmcdonnal

46,131
16
104
115

score 0 · Answer 3 · edited May 23 '17 at 12:20

0

You could use the Distinct method instead:

var newArray = oldArray.Distinct().ToArray();

This will obviously create a new array, instead of editing the original one.

Original answer

edited May 23 '17 at 12:20

Community

1
1

answered Feb 11 '14 at 23:12

Rodrigo Silva

432
1
6
18

Deleting duplicates in an array

3 Answers3