C# program to traverse a matrix in Spiral Form

Let's say we have a 4*4 matrix with the elements as

{1,2,3,4}
{5,6,7,8}
{9,10,11,12}
{13,14,15,16}

The objective is to visit this matrix in spiral manner such that the output will be

1 2 3 4 8 12 16 15 14 13 9 5 6 7 11 10

The below code will do so

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication2
{
    class Program
    {
        static List<int> res = new List<int>();

        static void Main(string[] args)
        {
            int row = 4;
            int col = 4;
            int[,] matrix = new int[4, 4] {
                                            {1,2,3,4},
                                            {5,6,7,8},
                                            {9,10,11,12},
                                            {13,14,15,16}
                                          };
           
            List<string> lstStr = new List<string>();            

            RowConstantColVary(0, 3, matrix);
            ColConstantRowVary(3, 3, matrix);
            RowConstantColVaryReverse(3, 2, matrix);
            ColConstantRowVaryReverse(2, 0, matrix);
            RowConstantColVary(1, 2, matrix);
            RowConstantColVaryReverse(2, 2, matrix);

            res.Take((row * col)).ToList().ForEach(i => Console.Write(i + " "));

            Console.ReadKey();

        }        

        private static void RowConstantColVary(int startRow, int endCol, int[,] matrix)
        {            
                for (int j = startRow; j <= endCol; j++)
                {               
                    res.Add(matrix[startRow, j]);
                }
            
        }
        private static void ColConstantRowVary(int endRow, int startCol, int[,] matrix)
        {
            for (int i = 1; i <= endRow; i++)
            {
                res.Add(matrix[i, startCol]);
            }

        }
        private static void RowConstantColVaryReverse(int startRow, int endCol, int[,] matrix)
        {
            for (int j = endCol; j >=0; j--)
            {              
                res.Add(matrix[startRow, j]);
            }

        }

        private static void ColConstantRowVaryReverse(int endRow, int startCol, int[,] matrix)
        {
            for (int i = endRow; i >= endRow-1; i--)
            {
                res.Add(matrix[i, startCol]);
            }

        }
    }
}