C# Trim spaces inside array (remove 0's)

How about with LINQ:

var result = arr.Where(x => x != 0).Concat(arr.Where(x => x == 0)).ToArray();

This is quite readable and has linear time complexity. On the other hand, it runs out-of-place and requires two passes over the input.

All the answers so far create a new array. Really you can just move the items up in a single loop and then fill the rest with 0s.

public static void ShiftZerosRight(this int[] arr)
{
    int j = 0;
    while (j < arr.Length && arr[j] != 0)
    {
        j++;
    }
    for (int i = j; i < arr.Length; i++)
    {
        if (arr[i] != 0)
        {
            arr[j++] = arr[i];
        }
    }
    while (j < arr.Length)
    {
        arr[j++] = 0;    
    }
}

Not as elegant as the single line LINQ expressions, but more efficient - this does not create any new objects (and LINQ creates several and the final new array) and this is a single pass through the array. As an extension method the complexity is not seen in the main body where it can be used as:

int arr[] = { ... };
arr.ShiftZerosRight();

Perhaps using Linq with:

        int[] arr = { 123, 243, 0, 0, 123, 0, 0, 0, 123 };

        arr = arr.OrderByDescending(a => a > 0).ToArray<int>();

Try this:

arr.OrderBy(x=>x == 0).ToArray();

Make a new array and transfer the values to it.

int[] newArr = new int[arr.Length];
int i = 0;
foreach ( var v in arr )
{
    if (v != 0) 
    {
        newArr[i++] = v;
    }
}
arr = newArr;

Since int is a value type the array is initialized with all zeroes. Then we copy the values one at a time only increasing the destination index i if the value is not 0. More verbose than the Linq examples shown, and decidedly uncooler. But if you're a student it might be easier to follow.

This code snippet doesn't create another array.Here 'x[]' is your array. You take the 1st 0 value and replace it with a non zero number.

int i=0,j=0,index=0,temp=0;
for(i=0;i<x.length;i++)
{
    if(x[i]==0)
    {
       index=i;
       for(j=index;j<x.length;j++)
       {
          if(x[j]!=0)
          {
            temp=x[j];
            x[j]=x[i];
            x[i]=temp;
            break;
          }
       }
    }
}