Character reverse in string by word Without predefined function in C#

class Program

    {

        static int k;

        static string[] SToArray(string str)

        {

            int size = 1;

            for (int i = 0; i < str.Length; i++)

            {

                if (str[i] == ' ')

                    size++;

            }

            string str1 = "";

            string[] sa = new string[size];

            for (int i = 0; i < str.Length; i++)

            {

                if (str[i] == ' ')

                {

                    sa[k] = str1;

                    str1 = "";

                    k++;

                }

                else

                    str1 += str[i];

                if (i == str.Length - 1)

                    sa[k] = str1;

            }

            return sa;

        }

        static void Main()

        {

            Console.WriteLine("Enter the string: ");

            string input = Console.ReadLine();

            string[] revers = SToArray(input);

            foreach (string item in revers)

            {

                for (int i = item.Length - 1; i >= 0; i--)

                {

                    Console.Write(item[i]);

                }

                Console.Write(" ");

            }

            Console.ReadLine();

        }

            }

Output: