Directories of removable disk Using DiretoryInfo

Question

Hi Programmers can you help me on how can i get the directories of a certain flash drive using DirectoryInfo in C#?

Vulpes · Answer

You didn't say which line was causing the error but if the variable 'drive' is still null that can only mean that the flash drive is not plugged in or is plugged in but isn't yet ready to be read. You can guard against this error by changing the code to the following: private button1_Click(object sender EventArgs e) { string drive = null; foreach (DriveInfo d in DriveInfo.GetDrives()) { if (d.IsReady && d.VolumeLabel == FLASHY) // or whatever { drive = d.Name; break; } } if (drive != null) { foreach(string dir in Directory.GetDirectories(drive)) { listBox1.Items.Add(Path.GetFileName(dir)); } } else { MessageBox.Show(Flash drive is not plugged in or is not yet ready); } }

Akemi Chou · Answer

Value cannot be null. There should be value :(

Vulpes · Answer

Well I just used a console app for simplicity to illustrate the code but you can easily put it into a Windows Forms app. For example: using System.IO; // ... private button1_Click(object sender EventArgs e) { string drive = null; foreach (DriveInfo d in DriveInfo.GetDrives()) { if (d.IsReady && d.VolumeLabel == FLASHY) // or whatever { drive = d.Name; break; } } foreach(string dir in Directory.GetDirectories(drive)) { listBox1.Items.Add(Path.GetFileName(dir)); } } Although it's possible to create or amend a volume label programatically I'd do it instead from the command prompt using the LABEL statement.

Akemi Chou · Answer

But I am using Windows form of C# how could I do that? :)

Vulpes · Answer

If no other removable drive will be plugged in at the same time as your flash drive then you could use this revised code to identify its drive letter and hence enumerate its directories: using System; using System.IO; class Test { static void Main() { string drive = null; foreach (DriveInfo d in DriveInfo.GetDrives()) { if (d.IsReady && d.DriveType == DriveType.Removable) { drive = d.Name; break; } } foreach(string dir in Directory.GetDirectories(drive)) { Console.WriteLine(Path.GetFileName(dir)); } Console.ReadKey(); } } Otherwise the only thing I can think of is to give it a unique Volume Label and then identify it from that: foreach (DriveInfo d in DriveInfo.GetDrives()) { if (d.IsReady && d.VolumeLabel == FLASHY) // or whatever { drive = d.Name; break; } } If the flash drive doesn't have a unique volume label already then you can give it one with the LABEL command: http://en.wikipedia.org/wiki/Label_(command)

Akemi Chou · Answer

I am so sorry for the inadequate and unspecific question. However thanks for your answer but my point is I wanted that the program will detect the certain flash drive without changing the location of a file because there are some instances that the Drive letter of some other removable disks are not permanent. Example of it; there are some which was located for I: or K: or G:. The question is; how can I make it default or let's just say the system could easily identify without mapping it manually with the use of DirectoryInfo? thanks for your reply :)

Vulpes · Answer

As long as the flash drive is mapped to a drive letter then you should be able to get a list of its directories in the same way as you would for a 'fixed' drive: using System; using System.IO; class Test { static void Main() { string drive = F:; // say foreach(string dir in Directory.GetDirectories(drive)) { Console.WriteLine(Path.GetFileName(dir)); } Console.ReadKey(); } }