Tutorial: Working with Files and Directories

The FileSystemInfo Class

One of the rich experiences in working with .NET is a huge collection of Base Class Libraries. The .NET Framework class library is a library of classes, interfaces, and value types that are included in the Microsoft .NET Framework SDK. This library provides access to system functionality and is designed to be the foundation on which .NET Framework applications, components, and controls are built.

The System.IO namespace contains types that allow synchronous and asynchronous reading and writing on data streams and files.

To parse information of lots of files and directories, the FileSystemInfo class comes in handy. It is an abstract class and contains members (methods, properties...) that are common to file and directory manipulation. A FileSystemInfo object can represent either a file or a directory. The implementation of this abstract class is done in FileInfo and DirectoryInfo class. The Members would take full path (absolute or relative) or UNC path if they require path as one of the parameters.

In VB6 you could have used the Scripting Library (FileSystemObject) to manipulate the Files and directories.

Listing1: Members of FileSystemInfo class (for more information refer to MSDN)

Attributes	Gets or sets the FileAttributes of the current FileSystemInfo.
CreationTime	Gets or sets the creation time of the current FileSystemInfo object.
Exists	Gets a value indicating whether the file or directory exists.
Extension	Gets the string representing the extension part of the file.
FullName	Gets the full path of the directory or file.
LastAccessTime	Gets or sets the time the current file or directory was last accessed.
LastWriteTime	Gets or sets the time when the current file or directory was last written to.
Name	For files, gets the name of the file. For directories, gets the name of the last directory in the hierarchy if a hierarchy exists. Otherwise, the Name property gets the name of the directory.
Delete	Deletes a file or directory.
FullPath	Represents the fully qualified path of the directory or file.
OriginalPath	The path originally specified by the user, whether relative or absolute.

The FileInfo class and DirectoryInfo class extends FileSystemInfo class and each add some more members to themselves for specific operations.

The FileInfo Class

The FileInfo class provides instance methods for the creation, copying, deletion, moving, and opening of files, and provides members to create FileStream objects.

Listing2: List of some members of FileInfo class (for more information refer to MSDN). I have excluded the members of FileSystemInfo class overridden by FileInfo class and implemented by FileSystemInfo class.
 

Directory	Gets an instance of the parent directory
DirectoryName	Gets a string representing the directory's full path.
Length	Gets the size of the current file or directory.
Name	Gets the name of the file.
Create	Creates a file.
CreateText	Creates a StreamWriter that writes a new text file.
Open	Opens a file with various read/write and sharing privileges
OpenRead	Creates a read-only FileStream.
OpenText	Creates a StreamReader with UTF8 encoding that reads from an existing text file.
OpenWrite	Creates a write-only FileStream
AppendText	Creates a StreamWriter that appends text to the file represented by this instance of the FileInfo.
CopyTo	Copies an existing file to a new file.
MoveTo	moves  an existing file to a new location

The DirectoryInfo Class

The DirectoryInfo class provides instance methods for creating, moving, and enumerating through directories and subdirectories.

Listing3: List of some members of DirectoryInfo class (for more information refer to MSDN), I have excluded the members of FileSystemInfo Class overridden by Directory class and implemented by FileSystemInfo class.
 

Parent	Gets the parent directory of a specified subdirectory
Root	Gets the root portion of a path.
Create	Creates a directory.
CreateSubDirectory	Creates a subdirectory or subdirectories on the specified path. The specified path can be relative to this instance of the DirectoryInfo class.
GetDirectories	Returns the subdirectories of the current directory
GetFiles	Returns a file list from the current directory
GetFileSystemInfos	Retrieves an array of strongly typed FileSystemInfo objects.
MoveTo	Moves a DirectoryInfo instance and its contents to a new path.

Below is an example of extending the FileSystemInfo class and adding IsDirectory

using System;
using System.IO;
public class CFileSystem:FileSystemInfo
{
FileInfo mobjFileInfo;
DirectoryInfo mobjDirectoryInfo;
bool mblnIsDirectory = true;
public CFileSystem(string xstrFilePath)
{
try
{
mobjDirectoryInfo = new DirectoryInfo(xstrFilePath);
if (!(mobjDirectoryInfo.Extension.Length==0))
{
mblnIsDirectory = false;
mobjDirectoryInfo= null;
mobjFileInfo = new FileInfo(xstrFilePath);
}
}
catch (Exception ex)
{
Console.WriteLine( ex.ToString());
}
public override void Delete()
{
if (mblnIsDirectory)
{
mobjDirectoryInfo.Delete();
}
else
{
mobjFileInfo.Delete();
}
}
public override bool Exists
{
get
{
if (mblnIsDirectory)
{
return mobjDirectoryInfo.Exists;
}
else
{
eturn mobjFileInfo.Exists;
}
}
}
public string Fullname
{
get
{
if (mblnIsDirectory)
{
return mobjDirectoryInfo.FullName;
}
else
{
return mobjFileInfo.FullName;
}
}
}
public override string Name
{
get
{
if (mblnIsDirectory)
{
return mobjDirectoryInfo.Name;
}
else
{
return mobjFileInfo.Name;
}
}
}
public bool IsDirectory
{
get
{
return mblnIsDirectory;
}
}
public bool IsFile
{
get
{
return !mblnIsDirectory;
}
}
}