Hi
Refer below one.

 string str;
 char[] arr1;
 char ch;
 int i, j, l;
 Console.Write("\n\nSort a string array in ascending order :\n");
 Console.Write("--------------------------------------------\n");
 Console.Write("Input the string : ");
        str = Console.ReadLine();
        l = str.Length;
        arr1 = str.ToCharArray(0, l);
 for (i = 1; i < l; i++)
 for (j = 0; j < l - i; j++)
 if (arr1[j] > arr1[j + 1])
 {
                    ch = arr1[j];
                    arr1[j] = arr1[j + 1];
                    arr1[j + 1] = ch;
 }
 Console.Write("After sorting the string appears like : \n");
 foreach (char c in arr1)
 {
            ch = c;
 Console.Write("{0} ", ch);
 }
 Console.WriteLine("\n");