The .NET Framework provides four basic classes for retrieving file system information. They are all located in the System.IO namespace.They include the following:

· Directory and File. These classes provide static methods that allow you to retrieve information about any files and directories that are visible from your server.

· DirectoryInfo and FileInfo. These classes use similar instance methods and properties to retrieve the same sort of information.

string directoryName = @”c:\Temp”;

// Retrieve the list of files, and display it in the page.
string[] fileList = Directory.GetFiles(ftpDirectory);

foreach (string file in fileList)
{
lstFiles.Items.Add(file);
}

DirectoryInfo and FileInfo:

DirectoryInfo myDirectory = new DirectoryInfo(@”c:\Temp”);
FileInfo myFile = new FileInfo(@”c:\Temp\readme.txt”);

You can create directory or file if doesn’t exist.

myDirectory.Create();
FileStream stream = myFile.Create();
stream.Close();

We can filter files using wildcards.

DirectoryInfo dir = new DirectoryInfo(@”c:\temp”);

// Get all the files with the .txt extesion.
FileInfo[] files = dir.GetFiles(“*.txt”);

We can retrieve full path of either file or directory using Path class.

String filename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory,txtfilename);

We can get particular file version using FileVersionInfo.

FileVersionInfo info = FileVersionInfo.GetVersionInfo((string)path);

Streams:
Streams are used to represent data in a memory buffers, data that’s being retrieved over a network.

FileStream fileStream = null;
try
{
fileStream = new FileStream(fileName, FileMode.Create);
fileStream.Write(bytes);
}

finally
{
if (fileStream != null) fileStream.Close();
}

We can create txt files using streamwriter,

string fileName = “sample.txt”;
using (FileStream fs = new FileStream(fileName, FileMode.Create))
{
StreamWriter w = new StreamWriter(fs);
w.WriteLine(DateTime.Now);
w.WriteLine(message);
w.Close();
}

Hope this helps for understanding files and streams.

Happy Coding.