Rename files in current folder based on modification date

renamer.cs

using System;
using System.IO;
namespace rename
{
    class Program
    {
        static void Main(string[] args)
        {
            var subfolderName = args?.Length > 0 ? args[0] : Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);

            int ind;
            var fileInfos = new DirectoryInfo(subfolderName).GetFiles("*", SearchOption.AllDirectories);
            for (ind = 0;ind < fileInfos.Length;ind++)
            {
                var fileInfo = fileInfos[ind];
                if (string.CompareOrdinal(fileInfo.Extension, ".exe") == 0)
                {
                    continue;
                }
                var destFileName = Path.Combine(fileInfo.DirectoryName, fileInfo.LastWriteTime.ToString("yyyy-MM-dd HH-mm") + fileInfo.Extension);
                MoveOrRename(fileInfo.FullName, destFileName);

                Console.WriteLine($@"Renamed {fileInfo.FullName} - {destFileName}");
            }

            Console.WriteLine($@"Files processed {ind}");
            Console.ReadLine();
        }

        public static bool EqualSize(string sourceFileName, string destFileName)
        {
            if (File.Exists(sourceFileName) && File.Exists(destFileName))
            {
                return new FileInfo(sourceFileName).Length == new FileInfo(destFileName).Length;
            }

            return false;
        }

        public static string MoveOrRename(string sourceFileName, string destFileName)
        {
            var fileName = Path.GetFileName(destFileName);
            var fileExt = Path.GetExtension(fileName);
            var folder = Path.GetDirectoryName(destFileName);

            int ind;
            bool skipMove = false;
            for (ind = 1; File.Exists(destFileName) && !(skipMove = EqualSize(sourceFileName, destFileName)); ind++)
            {
                destFileName = Path.Combine(folder, $@"{fileName}_{ind}{fileExt}");
            }

            if (!skipMove)
            {
                File.Move(sourceFileName, destFileName);
            }
            return destFileName;
        }
    }
}