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");
 }

Answer 1

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();

Answer 2

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

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

Answer 3

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