Search for a File or Directory

9/25/2010 3:18:07 PM

Problem : You need to find a file or directory by name, possibly with wildcards.

Solution: The DirectoryInfo object contains many useful functions, among them the ability to search the file system for files and folders containing a search pattern. The search pattern can contain wildcards, just as if you were using the command prompt.

Listing 1 provides a simple example that searches a directory tree for any file or directory that matches the input pattern.

Listing 1. Searching for a File or Directory

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

namespace Find
{
    class Program
    {
        static bool _folderOnly = false;
        static string _startFolder;
        static string _searchTerm;

        static void Main(string[] args)
        {
            if (!ParseArgs(args))
            {
                PrintUsage();
                return;
            }
            Console.WriteLine("Searching {0} for \"{1}\" {2}",
                _startFolder, _searchTerm,
                _folderOnly ? "(folders only)" : "");
            DoSearch();
        }

        private static void DoSearch()
        {
            DirectoryInfo di = new DirectoryInfo(_startFolder);
            DirectoryInfo[] directories = di.GetDirectories(_searchTerm,
                    SearchOption.AllDirectories);
            int numResults = directories.Length;
            PrintSearchResults(directories);
            if (!_folderOnly)
            {
                FileInfo[] files = di.GetFiles(
                             _searchTerm,
                             SearchOption.AllDirectories);
                PrintSearchResults(files);
                numResults += files.Length;
            }

            Console.WriteLine("{0:N0} results found", numResults);
        }

        private static void PrintSearchResults(
                                DirectoryInfo[] directories)
        {
              foreach(DirectoryInfo di in directories)
            {
                Console.WriteLine("{0}\t{1}\t{2}",
                 di.Name, di.Parent.FullName, "D");
            }
        }

        private static void PrintSearchResults(FileInfo[] files)
        {
             foreach(FileInfo fi in files)
            {
                Console.WriteLine("{0}\t{1}\t{2}",
                 fi.Name, fi.DirectoryName, "F");
            }
        }

        static void PrintUsage()
        {
            Console.WriteLine(
             "Usage: Find [-directory] SearchTerm StartFolder");
            Console.WriteLine("Ex: Find -directory code D:\\Projects");
            Console.WriteLine("* wildcards are accepted");

        }
        static bool ParseArgs(string[] args)
        {
            if (args.Length < 2)
            {
                return false;
            }
            if (string.Compare(args[0], "-directory") == 0)
            {
                _folderOnly = true;
                if (args.Length < 3)
                    return false;
            }
            _startFolder = args[args.Length - 1];
            _searchTerm = args[args.Length - 2];
            return true;
        }
    }
}

Here’s the program output (your results will likely vary):

D:\code\ch11\Find\bin\Debug>Find *media* "c:\Program Files" > temp.txt
Searching c:\Program Files for "*media*"
Windows Media Player         c:\Program Files                      D
VideoMediaHandler.dll        c:\Program Files\Movie Maker          F
VideoMediaHandler.dll.mui    c:\Program Files\Movie Maker\en-US    F
3 results found

Note

You may get an “access denied” error while running this program when the search runs across a folder you don’t have permission to access. One way to handle this is to change the search options to SearchOption.TopDirectoryOnly, track the subdirectories in a stack, and perform the recursive search yourself, handling the possible exceptions along the way.