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Directory.EnumerateDirectories Method (String, String, SearchOption)

Returns an enumerable collection of directory 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> EnumerateDirectories(
	string path,
	string searchPattern,
	SearchOption searchOption
)

Parameters

path
Type: System.String

The relative or absolute path to the directory to search. This string is not case-sensitive.

searchPattern
Type: System.String

The search string to match against the names of directories in path. This parameter can contain a combination of valid literal path and wildcard (* and ?) characters (see Remarks), but doesn't support regular expressions.

searchOption
Type: System.IO.SearchOption

One of the enumeration values 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 the full names (including paths) for the directories in the directory specified by path and that match the specified search pattern and option.

ExceptionCondition
ArgumentException

path is a zero-length string, contains only white space, or contains invalid characters. You can query for invalid characters by using the GetInvalidPathChars method.

- or -

searchPattern does not contain a valid pattern.

ArgumentNullException

path is null.

-or-

searchPattern is null.

ArgumentOutOfRangeException

searchOption is not a valid SearchOption value.

DirectoryNotFoundException

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

IOException

path is a file name.

PathTooLongException

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.

SecurityException

The caller does not have the required permission.

UnauthorizedAccessException

The caller does not have the required permission.

searchPattern can be a combination of literal and wildcard characters, but doesn't support regular expressions. The following wildcard specifiers are permitted in searchPattern.

Wildcard specifier

Matches

* (asterisk)

Zero or more characters in that position.

? (question mark)

Exactly one character in that position.

Characters other than the wildcard are literal characters. For example, the searchPattern string "*t" searches for all names in path ending with the letter "t". The searchPattern string "s*" searches for all names in path beginning with the letter "s".

searchPattern cannot end in two periods ("..") or contain two periods ("..") followed by DirectorySeparatorChar or AltDirectorySeparatorChar, nor can it contain any invalid characters. You can query for invalid characters by using the GetInvalidPathChars method.

You can specify relative or absolute path information in 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 returned directory names are prefixed with the value you provided in the path parameter. For example, if you provide a relative path in the path parameter, the returned directory names will contain a relative path.

The EnumerateDirectories and GetDirectories methods differ as follows: When you use EnumerateDirectories, you can start enumerating the collection of names before the whole collection is returned; when you use GetDirectories, 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, EnumerateDirectories 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 enumerates directories in a specified path that match a specified search pattern. It uses the searchOption parameter to specify that all subdirectories should be included in the search.

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

class Program
{

    private static void Main(string[] args)
    {
        try
        {
            string dirPath = @"\\archives\2009\reports";

            // LINQ query. 
            var dirs = from dir in 
                     Directory.EnumerateDirectories(dirPath, "dv_*",
                     	SearchOption.AllDirectories)
                       select dir;

            // Show results. 
            foreach (var dir in dirs)
            {
                // Remove path information from string.
                Console.WriteLine("{0}", 
                    dir.Substring(dir.LastIndexOf("\\") + 1));

            }
            Console.WriteLine("{0} directories found.", 
                dirs.Count<string>().ToString());

            // Optionally create a List collection.
            List<string> workDirs = new List<string>(dirs);
        }
        catch (UnauthorizedAccessException UAEx)
        {
            Console.WriteLine(UAEx.Message);
        }
        catch (PathTooLongException PathEx)
        {
            Console.WriteLine(PathEx.Message);
        }
    }
}

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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