Permutations of string like XYZ in C#

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DataStructureExam

{

    public class StrPre

    {

        public static void Main()

        {

            String str = "xyz";

            int n = str.Length;

            permute(str, 0, n - 1);

            Console.ReadLine();

        }

        public static void permute(string str, int first, int last)

        {

            if (first == last)

            {

                Console.WriteLine(str);

            }

            else

            {

                for (int i = first; i <= last; i++)

                {

                    char temp;

                    char[] charArray = str.ToCharArray();

                    temp = charArray[first];

                    charArray[first] = charArray[i];

                    charArray[i] = temp;

                    string str1 = new string(charArray);

                    permute(str1, first + 1, last);

                }

            }

        }

    }

}

Output: