C # and recursive algorithm to delete, empty, copy directory

Recursive algorithm, delete, empty, copy a folder.

the using the System.IO; 

namespace FileManagement 
{ 
    public  class MyFileManager 
    { 
        ///  <Summary> 
        /// remove a directory (empty or not)
         /// 1. delete all the files in the directory
         /// 2. delete All descendants of the directory in the directory
         /// 3. Finally, delete the directory (has become an empty directory)
         ///  </ the Summary> 
        ///  <param name = "dirName"> directory name </ param> 
        public  static  void RemoveDir ( String dirName) 
        { 
            IF (! Directory.Exists (dirName)) 
            { 
                return ; 
            }
            string[] fileNames = Directory.GetFiles(dirName);
            string[] dirNames = Directory.GetDirectories(dirName);
            foreach (string fileName in fileNames)
            {
                File.Delete(fileName);
            }
            foreach (string dirName_ in dirNames)
            {
                RemoveDir(dirName_);
            }
            Directory.Delete(dirName);
        }

        /// <summary>
        /// 清空一个目录
        ///1. Delete all files
        /// 2. Empty all of the descendants of the directory
         /// 3. Delete all of the descendants of the directory (has become an empty directory)
         ///  </ the Summary> 
        ///  <param name = "DirName"> directory name </ param> 
        public  static  void ClearDir ( String dirName) 
        { 
            IF (! Directory.Exists (dirName)) 
            { 
                return ; 
            } 
            String [] = fileNames the Directory.GetFiles (dirName);
             String [] = dirnames Directory.GetDirectories (dirName);
             the foreach ( String fileName fileNames)in 
            { 
                File.Delete (fileName); 
            } 
            the foreach ( String dirName_ in dirnames) 
            { 
                ClearDir (dirName_); 
                Directory.Delete (dirName_); 
            } 
        } 
        
        ///  <Summary> 
        /// the contents of a directory are copied to the other a directory
         ///  </ Summary> 
        ///  <param name = "sourceDir"> </ param> 
        ///  <param name = "targetDir"> </ param> 
        public  static  void copydir ( String sourceDir, String targetDir )
        {
            if (!Directory.Exists(targetDir))
            {
                Directory.CreateDirectory(targetDir);
            }
            string[] fileNames = Directory.GetFiles(sourceDir);
            string[] dirNames = Directory.GetDirectories(sourceDir);
            foreach (string fileName in fileNames)
            {
                File.Copy(fileName,targetDir + Path.DirectorySeparatorChar + Path.GetFileName(fileName),true);
            }
            foreach (string dirName_ in dirNames)
            {
                string[] splitStr = dirName_.Split(Path.DirectorySeparatorChar);
                CopyDir(dirName_, targetDir + Path.DirectorySeparatorChar + splitStr[splitStr.Length - 1]);
            }
        }
    }
}