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Directory.EnumerateFiles Method (String, String, SearchOption)

Returns an enumerable collection of file names that match a search pattern in a specified path, and optionally searches subdirectories.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

public static IEnumerable<string> EnumerateFiles(
	string path,
	string searchPattern,
	SearchOption searchOption


Type: System.String
The directory to search.
Type: System.String
The search string to match against the names of directories in path.
Type: System.IO.SearchOption
One of the values of the SearchOption enumeration that specifies whether the search operation should include only the current directory or should include all subdirectories.
The default value is TopDirectoryOnly.

Return Value

Type: System.Collections.Generic.IEnumerable<String>
An enumerable collection of file names in the directory specified by path and that match searchPattern and searchOption.


path is a zero-length string, contains only white space, or contains invalid characters as defined by GetInvalidPathChars.

- or -

searchPattern does not contain a valid pattern.


path is null.


searchPattern is null.


searchOption is not a valid SearchOption value.


path is invalid, such as referring to an unmapped drive.


path is a file name.


The specified path, file name, or combined exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters and file names must be less than 260 characters.


The caller does not have the required permission.


The caller does not have the required permission.

The following wildcard specifiers are permitted in the searchPattern parameter.

Wildcard character



Zero or more characters.


Exactly one character.

You can specify relative path information with the path parameter. Relative path information is interpreted as relative to the current working directory, which you can determine by using the GetCurrentDirectory method.

The EnumerateFiles and GetFiles methods differ as follows: When you use EnumerateFiles, you can start enumerating the collection of names before the whole collection is returned; when you use GetFiles, you must wait for the whole array of names to be returned before you can access the array. Therefore, when you are working with many files and directories, EnumerateFiles can be more efficient.

The returned collection is not cached; each call to the GetEnumerator on the collection will start a new enumeration.

The following example recursively enumerates all files that have a .txt extension, reads each line of the file, and displays the line if it contains the string "Microsoft".

using System;
using System.IO;
using System.Linq;

class Program
    static void Main(string[] args)

            var files = from file in Directory.EnumerateFiles(@"c:\",
                            "*.txt", SearchOption.AllDirectories)
                        from line in File.ReadLines(file)
                        where line.Contains("Microsoft")
                        select new
                            File = file,
                            Line = line

            foreach (var f in files)
                Console.WriteLine("{0}\t{1}", f.File, f.Line);
			Console.WriteLine("{0} files found.", 
        catch (UnauthorizedAccessException UAEx)
        catch (PathTooLongException PathEx)

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.