sort array of int values without using built-in functions (using Bubble sort)

string res = "";
int[] arr = { 800, 11, 50, 771, 649, 770, 240, 9 };
for (int k = 0; k < arr.Length; k++)
{
for (int i = 0; i < arr.Length - 1; i++)
{
if (arr[i] > arr[i + 1])
{
int hold = arr[i + 1];
arr[i + 1] = arr[i];
arr[i] = hold;
}
}
res += arr[k].ToString();
arr[k] = arr[k];
}

string s = "1,2,3,,3,2";
string[] ss = (s.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries));
for (int k = 1; k < ss.Length; k++)
{
for (int i = 0; i < (ss.Length - 1); i++)
{
if (Convert.ToInt32(ss[i].Trim()) > Convert.ToInt32(ss[i + 1].Trim()))
{
string hold = ss[i];
ss[i] = ss[i + 1];
ss[i + 1] = hold;
}
}
}
s = string.Join(",", ss);