Streams are used for random or sequential access to data within .NET Framework. There is an abstract class that implements all the required methods and properties. Here is a list.

Properties

 

Name	Description
CanRead	Decides if stream supports reading.
CanSeek	Decides if stream supports seeking.
CanTimeout	Decides if stream can time out.
CanWrite	Decides whether the stream can be written to.
Length	Determines the length of the stream.
Position	Determines or sets the virtual cursor.
ReadTimeout	Determines or sets the stream's timeout for read.
WriteTimeout	Determines or sets the stream's timeout for write.

Methods

 

Name	Description
Close	Closes the stream and discharge any resources.
Flush	Clears out any buffers within the stream.
Read	Sequential read of a specified number of bytes.
ReadByte	Does the read of a single byte and updates position by one.
Seek	Sets the position within the stream.
SetLength	Determines the length of the stream.
Write	Writes information to the stream.
WriteByte	Writes a single byte to the stream.

All the Stream Classes such as FileStream (System.IO), MemoryStream (System.IO), CryptoStream (System.Security), NetworkStream (System.Net), GZipStream (System.Compression) derived from Stream Class. The main reason is that they are all working in a similar way.
//Display Stream
static void DumpMyStream(Stream theMyStream)
{
    theMyStream.Position = 0;
    while (theMyStream.Position != theMyStream.Length)
    {
        Console.WriteLine("{0:x2}", theMyStream.ReadByte());
    }
}

We require a file to read from or to it with the help of Stream class or its derivatives. In order to access file and assist Stream class to work with the file we employ File class.

Methods of the File class

 

Name	Description
AppendAllText	Appends a string into a file.
AppendText	Opens a file with the StreamWriter.
Copy	Copies a file to a new file.
Create	Creates a new file.
CreateText	Creates or opens a file.
Move	Moves a file from one place to another.
Open	Opens an existing file.
OpenRead	Reads an existing read-only file.
OpenText	Reads an existing file.
OpenWrite	Reads an existing file for writing.
ReadAllBytes	Reads a file, reads the contents.
ReadAllLines	Reads a file, reads the contents of it into an array of strings.
ReadAllText	Reads the contents of it into a string.
WriteAllBytes	Writes a file content of a byte array.
WriteAllLines	Writes a file, writes the contents of a string array.
WriteAllText	Writes the contents of a string into a file.

In addition to File class that helps us to work with files, .NET Framework provides Directory class which helps us to work with directories as its name suggests.

Methods

 

Name	Description
CreateDirectory	Creates the directories.
Delete	Deletes a directory.
Exists	Checks for existence.
GetCreationTime	Get time and date of a directory creation.
GetCurrentDirectory	Gets a DirectoryInfo object.
GetDirectories	Gets names for subdirectories.
GetDirectoryRoot	Gets the volume and/or root information.
GetFiles	Gets the names of files.
GetFileSystemEntries	Gets a list of subdirectories.
GetLastAccessTime	Gets the time that dir. was last accessed.
GetLastWriteTime	Gets the time that dir. was last written to.
GetLogicalDrives	Gets a list of drives.
GetParent	Gets the parent directory.
Move	Moves a file or directory.
SetCreationTime	Sets the time a when directory was created.
SetCurrentDirectory	Sets the specified directory to be the current working directory.
SetLastAccessTime	Sets the time a directory was accessed.
SetLastWriteTime	Sets the time a directory was written to.

In order to access file we need to set a mode in which way we want to access Read/Write. In order to do that we use FileAccess enumeration this has following members.

 

Name	Description
Read	Open with read-only access.
Write	Open for write access only.
ReadWrite	Open for read/write access.

FileMode enumeration determines how we are going to work with the file. We can open file, create new one and etc… Its main members are:

 

Name	Description
Append	Append a file and moves the pointer in the FileStream.
Create	Creates a new file.
CreateNew	Creates a new file with the exception thrown.
Open	Opens an existing file.
OpenOrCreate	Opens an existing file or creates new.
Truncate	Opens and Trancates file.

Additional classes which are important to know: FileStream class used to open file stream for reading or writing.

Properties

 

Name	Description
Handle	Determines the stream's file handle.
Name	Determines the name of the file.

Methods

 

Name	Description
Lock	Lock file for changes.
Unlock	Unlocks file for changes.

StreamReader class as its name suggests is used for reading streams.

Properties

 

Name	Description
BaseStream	Gets the base stream.
CurrentEncoding	Gets the encoding used for the stream.
EndOfStream	Determines the end of the stream.

Methods

 

Name	Description
Close	Closes the reader and the stream.
Peek	Returns the next character without moving.
Read	Reads the next set of characters.
ReadBlock	Reads the next block of characters.
ReadLine	Reads the next line of characters.
ReadToEnd	Reads all the characters till the end of the stream.

Reading from the file is simple, we first open file like that. FileStream is already buffered stream so it does not require BufferedStream object.
FileStream myFileStream = File.Open(@"C:\boot.ini", FileMode.Open, FileAccess.Read);

In order to read this file we can use Read class but better way is to utilize StreamReader class
StreamReader myRDR = new StreamReader(myFileStream);
Console.Write(myRDR.ReadToEnd());
myRDR.Close();
myFileStream.Close();

Or you can use the following way of opening and reading file. Here we can see that File class supports StreamReader
StreamReader myRDR = File.OpenText(@"C:\bootfile.ini");
Console.Write(myRDR.ReadToEnd());
myRDR.Close();

StreamWriter Class is similar to StreamReader in several ways; it uses File class pretty much the same way as StreamReader.

Properties

 

Name	Description
AutoFlush	Gets or sets an indicator that shows flush changes to the stream.
BaseStream	Gets the current stream.
Encoding	Gets the current encoding used for the stream.
NewLine	Gets or sets a string that contains the line terminator string.

Methods

 

Name	Description
Close	Closes the writer of the stream.
Write	Writes to the stream.
WriteLine	Writes data to the stream with line end.

Example if writing a file in C# as follows.

Open file
FileStream myFileStream = File.Create(@"c:\somefilestream.txt");

Write to file
StreamWriter myWriter = new StreamWriter(myFileStream);
myWriter.WriteLine("Hello");
myWriter.Close();
myFileStream.Close();