计算文件扩展名C＃

Question

Hi i'm ac# begginer and i'd like to do a simple program which is going to go through a folder and count how many files are .mp3 files and how many are .flac .

Like I said the program is very basic. It will ask for the music folder path and will then go through it. I know there will be a lot of subfolders in that main music folder so it will have to open them one at the time and go through them too.

Eg

C:/Music/ will be the given directory. But it doesn't contain any music in itself. To get to the music files the program would have to open subfolders like

C:/Music/Electronic/deadmau5/RandomAlbumTitle/ Only then he can count the .mp3 files and .flac files and store them in two separated counters. The program will have to do that for at least 2000 folders.

Do you know a good way or method to go through files and return its name (and extension)?

Answer 1

You can use System.IO.DirectoryInfo . DirectoryInfo provides a GetFiles method, which also has a recursive option, so if you're not worried about speed, you can do this:

DirectoryInfo di = new DirectoryInfo(@"C:\Music");

int numMP3 = di.GetFiles("*.mp3", SearchOption.AllDirectories).Length;
int numFLAC = di.GetFiles("*.flac", SearchOption.AllDirectories).Length;

Answer 2

Use DirectoryInfo and a grouping by the file extension:

var di = new DirectoryInfo(@"C:/Music/");
var extensionCounts = di.EnumerateFiles("*.*", SearchOption.AllDirectories)
                        .GroupBy(x => x.Extension)
                        .Select(g => new { Extension = g.Key, Count = g.Count() })
                        .ToList();

foreach (var group in extensionCounts)
{
    Console.WriteLine("There are {0} files with extension {1}", group.Count, 
                                                                group.Extension);
}

Answer 3

C# has a built in method of searching for files in all sub-directories. Make sure you add a using statement for System.IO

var path = "C:/Music/"
var files = Directory.GetFiles(path, "*.mp3", SearchOption.AllDirectories);
var count = files.Length;

Since you're a beginner you should hold off on the more flexible LINQ method until later.

Answer 4

int fileCount = Directory.GetFiles(_Path, "*.*", SearchOption.TopDirectoryOnly).Length

Answer 5

Duplicate question How to read File names recursively from subfolder using LINQ

Jon Skeet answered there with

You don't need to use LINQ to do this - it's built into the framework :

string[] files = Directory.GetFiles(directory, "*.dll",
                                    SearchOption.AllDirectories);

or if you're using .NET 4 :

IEnumerable<string> files = Directory.EnumerateFiles(directory, "*.dll",
                                                    SearchOption.AllDirectories);

To be honest, LINQ isn't great in terms of recursion. You'd probably want to write your own general-purpose recursive extension method. Given how often this sort of question is asked, I should really do that myself some time...

Answer 6

Here is MSDN support page, How to recursively search directories by Visual C#

Taken directly from that page:

void DirSearch(string sDir) 
{
    try 
    {
       foreach (string d in Directory.GetDirectories(sDir)) 
       {
        foreach (string f in Directory.GetFiles(d, txtFile.Text)) 
        {
           lstFilesFound.Items.Add(f);
        }
        DirSearch(d);
       }
    }
    catch (System.Exception excpt) 
    {
        Console.WriteLine(excpt.Message);
    }
}

You can use this code in addition to creating FileInfo objects. Once you have the file info objects you can check the Extension property to see if it matches the ones you care about.

Answer 7

MSDN有很多信息和示例，例如如何遍历目录： http ： //msdn.microsoft.com/en-us/library/bb513869.aspx