C# List Directory

Summary: in this tutorial, you’ll learn how to list a directory in C# using the Directory.EnumerateDirectories() method.

Introduction to the C# Directory.EnumerateDirectories() method

The Directory.EnumerateDirectories() method returns an enumerable collection (IEnumerable<string>) of directory names that match a specified search pattern.

Here’s the syntax of the Directory.EnumerateDirectories() method:

public static IEnumerable<string> EnumerateDirectories(
    string path, 
    string searchPattern, 
    SearchOption searchOption
);Code language: C# (cs)

In this syntax:

• The path specifies the path of the directory to search for subdirectories.
• The searchPattern specifies a search pattern.
• The searchOption instructs the method to search only the current directory (SearchOption.TopDirectoryOnly) or include all subdirectories (SearchOptioin.AllDirectories).

The search pattern can contain wildcards like * and ?:

• Asterisk (*) – matches zero or more characters.
• Question mark (?) – matches exactly one character.

For example:

• backup* matches a string that starts with backup and is followed by zero or more characters e..g, backup2023, backupABC.
• backup? matches a string that starts with backup and is followed by a character e.g., backup1, backup2.

Besides invalid characters, the search pattern cannot end with two periods (..) or contain two periods (..)

Note that the searchPattern doesn’t support regular expressions.

C# listing directory example

The following program demonstrates how to find the directories whose names start with "0" in the C:\backup directory:

using static System.Console;

string path = @"C:\backup\2023";

var dirnames = Directory.EnumerateDirectories(
    path,
    "0*",
    SearchOption.AllDirectories
);

foreach (var dirname in dirnames)
{
    WriteLine(dirname);
}Code language: C# (cs)

Suppose the C:\backup directory is like this:

c:\backup
└── 2023
   ├── 01
   |  └── readme.txt
   ├── 02
   ├── 03
   ├── 04
   ├── 05
   ├── 06
   ├── 07
   ├── 08
   ├── 09
   ├── 10
   ├── 11
   └── 12

directory: 13 file: 1Code language: plaintext (plaintext)

The program will show the following output:

C:\backup\2023\01
C:\backup\2023\02
C:\backup\2023\03
C:\backup\2023\04
C:\backup\2023\05
C:\backup\2023\06
C:\backup\2023\07
C:\backup\2023\08
C:\backup\2023\09Code language: plaintext (plaintext)

Summary

• Use C# Directory.EnumerateDirectories() method to return an IEnumerable<string> of paths to directories that match specified criteria.