C# Directory Type

This C# page uses the Directory type. This class contains many methods that interact with the file system.
Directory, System.IO. The Directory type is found in System.IO. It provides methods that interact with the file system's concept of folders.File
With this class, we create directories, get file lists from directories, test directories for existence, and delete directories. Directory is often used with Path.Directory.GetFilesPath
EnumerateFiles. Many methods on the Directory type are available. We call them as static methods: to call EnumerateFiles, we can use Directory.EnumerateFiles.Static

Note: For this method, we receive one path string at a time. EnumerateFiles returns an IEnumerable collection.

And: With a foreach-loop, we can get each string one at a time. If there are many files, this can avoid a large array creation.

IEnumerableForeach
C# program that uses EnumerateFiles using System; using System.IO; class Program { static void Main() { // Returns an IEnumerable<string>. foreach (string path in Directory.EnumerateFiles("C:\\")) { Console.WriteLine(path); } } }
Performance, EnumerateFiles. I tested the Directory.EnumerateFiles method against GetFiles(). I tested 2 directories of varying file counts.Array

Next: We see that for a directory with 113 files, GetFiles is faster. But for a directory with 1251 files, EnumerateFiles is faster.

Info: The explanation for this is that an array creation of 1251 elements is avoided with EnumerateFiles.

Benchmark
EnumerateFiles code fragment: C# foreach (string path in Directory.EnumerateFiles("C:\\")) { } GetFiles code fragment: C# string[] paths = Directory.GetFiles("C:\\"); foreach (string path in paths) { } Time results: 113 files EnumerateFiles: 463681.00 ns GetFiles: 448693.00 ns (faster) Time results: 1251 files EnumerateFiles: 3128232.00 ns (faster) GetFiles: 3197795.00 ns
Exists. If you want to be certain that a directory exists, use the Directory.Exists method. A directory could be moved or deleted at any time. So code must still handle exceptions.

Tip: The Directory.Exists method can be accessed most easily if you add using System.IO to the top of your program.

Tip 2: The method returns a bool: true if the directory is present, and false if it is not.

Bool MethodTrue, False
C# program that uses Directory.Exists using System; using System.IO; class Program { static void Main() { if (Directory.Exists("C:\\Users")) { Console.WriteLine("Users"); } if (Directory.Exists("C:\\Losers")) { Console.WriteLine("Losers"); } } } Output Users
CreateDirectory. The Directory class helpfully provides support for creating a new directory. The CreateDirectory method makes new folders.Directory.CreateDirectory
DirectoryInfo. The DirectoryInfo is another way of accessing the Directory type functionality. We access important properties and methods on a DirectoryInfo.

Tip: We create DirectoryInfo by passing a directory path to its constructor. DirectoryInfo is a class.

Next: This program gets the name of the directory from DirectoryInfo, and then gets the file count for the directory.

C# program that uses DirectoryInfo using System; using System.IO; class Program { static void Main() { // Get info. DirectoryInfo info = new DirectoryInfo(@"C:\perls\"); // Write name. Console.WriteLine(info.Name); // Write file count. FileInfo[] array = info.GetFiles(); Console.WriteLine(array.Length); } } Output perls 5
Size. There are many ways to sum the total size of a directory. With one approach, we call GetFiles and loop through all the file names. We use the FileInfo type on each file name.Directory Size

And: Another option is to use the DirectoryInfo type. Then call the GetFileSystemInfos method to get all the FileInfos at once in an array.

GetFileSystemInfos
Exception. One exception that can be thrown is DirectoryNotFoundException. If you call Directory.GetFiles, and the Directory does not exist, this exception will be provoked.DirectoryNotFoundException
GetDirectoryName. The Path type provides a GetDirectoryName method. This receives a string argument and returns the directory part of that path string.Path.GetDirectoryName
DriveInfo. A drive is a physical directory on your computer. The C drive is often the main hard drive on a Windows computer. DriveInfo helps us handle drives.DriveInfo
Windows. In Windows Forms, the FolderBrowserDialog provides a window that displays folder hierarchies. This avoids the need for custom code.FolderBrowserDialog

Also: The OpenFileDialog allows users to browse directories and open files, not just other folders.

OpenFileDialog
FileSystemWatcher. We can use the FileSystemWatcher type to get notifications when a file changes in a directory. Then, we can update our memory model of the file system.FileSystemWatcher

Tip: This makes it possible to access the file system only when needed. It makes using a cache of file names more effective.

A summary. For interacting with the file system and using folders, the Directory type is helpful. Other types, such as Path, help with directory-handling code.
© 2007-2019 Sam Allen. Every person is special and unique. Send bug reports to info@dotnetperls.com.
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