IO (Input and Output)

(Input and output)StreamsAll input and output in the .NET Framework involves the use of streams. A stream is an abstract Representation of a serial device. A serial device is something that stores data in a linear manner and is accessed the same way: one byte at a time. This device can be a disk file, a network channel, a memory location, or any other object that supports reading and writing to it in a linear manner. Keeping the device abstract means that the underlying destination/source of the stream can be hidden. There are two types of streams: ➤ Output—Output streams are used when data is written to some external destination, which
can be a physical disk file, a network location, a printer, or another program.➤ Input— Input streams are used to read data into memory or variables that your program can
Access.THE CLASSES FOR INPUT AND OUTPUTSystem.IO contains the classes for reading and writing data to and from files, and you can reference this
namespace in your C# application to gain access to these classes without fully qualifying type names.CLASS DESCRIPTIONFile àA static utility class that exposes many static methods for moving, copying,
and deleting files.Directoryà A static utility class that exposes many static methods for moving, copying,
and deleting directories.Pathà A utility class used to manipulate path names.
FileInfoà Represents a physical file on disk, and has methods to manipulate this file.
For any reading from and writing to the file, a Stream object must be created.DirectoryInfo à Represents a physical directory on disk and has methods to manipulate this
directory.FileSystemInfo  Serves as the base class for both FileInfo and DirectoryInfo, making it possible to deal with files and directories at the same time using polymorphism.
FileStream  Represents a file that can be written to or read from, or both. This file can be written to and read from asynchronously or synchronously.
StreamReader  Reads character data from a stream and can be created by using a
FileStream as a base.StreamWriter  Writes character data to a stream and can be created by using a FileStream as a base.
FileSystemWatcher  It is used to monitor files and directories, and it exposes events that your application can catch when changes occur in these locations. This functionality has always been missing from Windows programming, but now the .NET Framework makes it much easier to respond to file system events
System.IO.Compression namespace, which enables you to read from and write
to compressed files, by using either GZIP compression or the Deflate compression scheme:➤ DeflateStream— Represents a stream in which data is compressed automatically when writing,
or uncompressed automatically when reading. Compression is achieved using the Deflatealgorithm.➤ GZipStream —Represents a stream in which data is compressed automatically when writing,
or uncompressed automatically when reading. Compression is achieved using the GZIPalgorithm.The File and Directory ClassesThe File and Directory utility classes expose many static methods for manipulating, surprisingly
enough, files and directories.Copy() Copies a file from a source location to a target location.
Create() Creates a file in the specified path.
Delete() Deletes a file.
Open() Returns a FileStream object at the specified path.
Move() Moves a specified file to a new location. You can specify a different name for the file in the new location.
Some useful static methods of the Directory class are shown in the next table:
METHOD DESCRIPTIONCreateDirectory() Creates a directory with the specified path.
Delete() Deletes the specified directory and all the files within it.
GetDirectories() Returns an array of string objects that represent the names
of the directories below the specified directory.EnumerateDirectories() Like GetDirectories(), but returns an IEnumerable<string> collection of directory names.
GetFiles() Returns an array of string objects that represent the names
of the files in the specified directory.EnumerateFiles() Like GetFiles(), but returns an IEnumerable<string> collection
of filenames.GetFileSystemEntries() Returns an array of string objects that represent the names
of the files and directories in the specified directory.EnumerateFileSystemEntries() Like GetFileSystemEntries(), but returns an IEnumerable<string> collection of file and directory names.
Move() Moves the specified directory to a new location. You can specify a new name for the folder in the new location.