Array Directory.GetFiles enum File IEnumerable List

Recursive file list

Directories are often nested. Sometimes we need a list of files in a folder, and also those in each subdirectory.

`AllDirectories`

The .NET Framework allows a SearchOption.AllDirectories argument to the Directory.GetFiles and EnumerateFiles methods. This is the easiest way to recursively get files.

`GetFiles`

This program gets a string array of all the files at a certain level of the file system. It also covers all sublevels. Then, it loops through the result and prints the file paths.

Tip You can see that the first level files in the specified directory are printed, and then all subdirectory files as well.

Argument 1 The first argument to Directory.GetFiles is the starting path. You must escape the backslashes in Windows paths.

Argument 2 The second argument is the universal pattern for file names. If you change the asterisks to a string, you can filter files.

Detail The third argument is the enumerated constant SearchOption.AllDirectories, which indicates you want a recursive file search.

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Get list of files in the specific directory.
        // ... Please change the first argument.
        string[] files = Directory.GetFiles("C:\\PerlsComStage\\",
            "*.*",
            SearchOption.AllDirectories);

        // Display all the files.
        foreach (string file in files)
        {
            Console.WriteLine(file);
        }
    }
}C:\PerlsComStage\Default.aspx
C:\PerlsComStage\Global.asax
C:\PerlsComStage\Web.config
C:\PerlsComStage\bin\PerlsComWebProject1.dll
C:\PerlsComStage\bin\PerlsComWebProject1.pdb

`List` example

We convert the array returned by Directory.GetFiles to a List. Then we pass the List instance to another method and display the value returned by its Count property.

Note In early versions of the .NET Framework, it may have been necessary to implement custom recursive file search algorithms.

But Today these methods are unnecessary because they overlap with existing functionality.

using System;
using System.Collections.Generic;
using System.IO;

class Program
{
    static void Main()
    {
        // Make sure directory exists before using this!
        var files = new List<string>(Directory.GetFiles("C:\\folder",
            "*.*",
            SearchOption.AllDirectories));
        Method(files);
    }

    static void Method(List<string> files)
    {
        Console.WriteLine(files.Count);
    }
}
22

`EnumerateFiles`

This method receives the directory path as its first argument. The second two arguments are optional. To recurse through directories, use AllDirectories.

Tip With EnumerateFiles, we receive an IEnumerable string. This must be evaluated in a foreach-loop or extension method.

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // Call EnumerateFiles in a foreach-loop.
        foreach (string file in Directory.EnumerateFiles(@"c:\files",
            "*.*",
            SearchOption.AllDirectories))
        {
            // Display file path.
            Console.WriteLine(file);
        }
    }
}c:\files\index.html
c:\files\style.css
c:\files\images\logo.png
c:\files\images\picture.jpg

Notes, custom methods

It is possible to develop a method that uses recursion, or stack-based recursion, to scan directories. This is fun to do, and may be a good learning experience.

But For real programs, using AllDirectories is probably a much better choice due to its well-tested implementation.

A summary

Directory.GetFiles method can perform a recursive file listing. Instead of custom implementations, this method overload provides a clearer, simpler abstraction.

Recursive file list

AllDirectories

GetFiles