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Device I/O
 Stream Class
  Constructors
  Fields
  Properties
  Methods
  Extension Methods
  Remarks
  Applies to
  See also
 BufferedStream Class
  Constructors
  Properties
  Methods
  Remarks
  Applies to
  See also
 Source/Reference

Device I/O

The main components used in .NET framework to access the device i/o are Stream, BufferedStream, FileStream, MemoryStream, StreamReader, StreamWriter, StringReader, StringWriter, TextReader, TextWriter, BinaryReader, and BinaryWriter.

Stream Class

Provides a generic view of a sequence of bytes. This is an abstract class.

NamespaceSystem.IO AssembliesSystem.IO.dll, mscorlib.dll, netstandard.dll, System.Runtime.dll
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public abstract class Stream : MarshalByRefObject, IDisposable

Inheritance: Object->->MarshalByRefObject->Stream

Derived: COMCharStream, OracleBFile, OracleLob, SqlFileStream, BufferedStream, FileStream, MemoryStream, UnmanagedMemoryStream, BrotliStream, DeflateStream, GZipStream, IsolatedStorageFileStream, PipeStream, AuthenticatedStream, NetworkStream, PrintQueueStream, CryptoStream

Attributes: ComVisibleAttribute, SerializableAttribute

Implements: IDisposable

Constructors

Stream()

Initializes a new instance of the Stream class.

Fields

Null

A Stream with no backing store.

Properties

CanRead

When overridden in a derived class, gets a value indicating whether the current stream supports reading.

CanSeek

When overridden in a derived class, gets a value indicating whether the current stream supports seeking.

CanTimeout

Gets a value that determines whether the current stream can time out.

CanWrite

When overridden in a derived class, gets a value indicating whether the current stream supports writing.

Length

When overridden in a derived class, gets the length in bytes of the stream.

Position

When overridden in a derived class, gets or sets the position within the current stream.

ReadTimeout

Gets or sets a value, in milliseconds, that determines how long the stream will attempt to read before timing out.

WriteTimeout

Gets or sets a value, in milliseconds, that determines how long the stream will attempt to write before timing out.

Methods

BeginRead(Byte[], Int32, Int32, AsyncCallback, Object)

Begins an asynchronous read operation. (Consider using ReadAsync(Byte[], Int32, Int32) instead.)

BeginWrite(Byte[], Int32, Int32, AsyncCallback, Object)

Begins an asynchronous write operation. (Consider using WriteAsync(Byte[], Int32, Int32) instead.)

Close()

Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream. Instead of calling this method, ensure that the stream is properly disposed.

CopyTo(Stream)

Reads the bytes from the current stream and writes them to another stream.

CopyTo(Stream, Int32)

Reads the bytes from the current stream and writes them to another stream, using a specified buffer size.

CopyToAsync(Stream)

Asynchronously reads the bytes from the current stream and writes them to another stream.

CopyToAsync(Stream, Int32)

Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size.

CopyToAsync(Stream, Int32, CancellationToken)

Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size and cancellation token.

CreateObjRef(Type)

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.

(Inherited from MarshalByRefObject)
CreateWaitHandle()

Allocates a WaitHandle object.

Dispose()

Releases all resources used by the Stream.

Dispose(Boolean)

Releases the unmanaged resources used by the Stream and optionally releases the managed resources.

EndRead(IAsyncResult)

Waits for the pending asynchronous read to complete. (Consider using ReadAsync(Byte[], Int32, Int32) instead.)

EndWrite(IAsyncResult)

Ends an asynchronous write operation. (Consider using WriteAsync(Byte[], Int32, Int32) instead.)

Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
Flush()

When overridden in a derived class, clears all buffers for this stream and causes any buffered data to be written to the underlying device.

FlushAsync()

Asynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device.

FlushAsync(CancellationToken)

Asynchronously clears all buffers for this stream, causes any buffered data to be written to the underlying device, and monitors cancellation requests.

GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetLifetimeService()

Retrieves the current lifetime service object that controls the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
GetType()

Gets the Type of the current instance.

(Inherited from Object)
InitializeLifetimeService()

Obtains a lifetime service object to control the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
MemberwiseClone(Boolean)

Creates a shallow copy of the current MarshalByRefObject object.

(Inherited from MarshalByRefObject)
ObjectInvariant()

Provides support for a Contract.

Read(Byte[], Int32, Int32)

When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.

ReadAsync(Byte[], Int32, Int32)

Asynchronously reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.

ReadAsync(Byte[], Int32, Int32, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

ReadByte()

Reads a byte from the stream and advances the position within the stream by one byte, or returns -1 if at the end of the stream.

Seek(Int64, SeekOrigin)

When overridden in a derived class, sets the position within the current stream.

SetLength(Int64)

When overridden in a derived class, sets the length of the current stream.

Synchronized(Stream)

Creates a thread-safe (synchronized) wrapper around the specified Stream object.

ToString()

Returns a string that represents the current object.

(Inherited from Object)
Write(Byte[], Int32, Int32)

When overridden in a derived class, writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.

WriteAsync(Byte[], Int32, Int32)

Asynchronously writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.

WriteAsync(Byte[], Int32, Int32, CancellationToken)

Asynchronously writes a sequence of bytes to the current stream, advances the current position within this stream by the number of bytes written, and monitors cancellation requests.

WriteByte(Byte)

Writes a byte to the current position in the stream and advances the position within the stream by one byte.

Extension Methods

Remarks

Stream is the abstract base class of all streams. A stream is an abstraction of a sequence of bytes, such as a file, an input/output device, an inter-process communication pipe, or a TCP/IP socket. The Stream class and its derived classes provide a generic view of these different types of input and output, and isolate the programmer from the specific details of the operating system and the underlying devices.

Streams involve three fundamental operations:

  • You can read from streams. Reading is the transfer of data from a stream into a data structure, such as an array of bytes.

  • You can write to streams. Writing is the transfer of data from a data structure into a stream.

  • Streams can support seeking. Seeking refers to querying and modifying the current position within a stream. Seek capability depends on the kind of backing store a stream has. For example, network streams have no unified concept of a current position, and therefore typically do not support seeking.

Some of the more commonly used streams that inherit from Stream are FileStream, and MemoryStream.

Depending on the underlying data source or repository, streams might support only some of these capabilities. You can query a stream for its capabilities by using the CanRead, CanWrite, and CanSeek properties of the Stream class.

The Read and Write methods read and write data in a variety of formats. For streams that support seeking, use the Seek and SetLength methods and the Position and Length properties to query and modify the current position and length of a stream.

This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic.

Disposing a Stream object flushes any buffered data, and essentially calls the Flush method for you. Dispose also releases operating system resources such as file handles, network connections, or memory used for any internal buffering. The BufferedStream class provides the capability of wrapping a buffered stream around another stream in order to improve read and write performance.

Starting with the .NET Framework 4.5, the Stream class includes async methods to simplify asynchronous operations. An async method contains Async in its name, such as ReadAsync, WriteAsync, CopyToAsync, and FlushAsync. These methods enable you to perform resource-intensive I/O operations without blocking the main thread. This performance consideration is particularly important in a Windows 8.x Store app or desktop app where a time-consuming stream operation can block the UI thread and make your app appear as if it is not working. The async methods are used in conjunction with the async and await keywords in Visual Basic and C#.

When used in a Windows 8.x Store app, Stream includes two extension methods: AsInputStream and AsOutputStream. These methods convert a Stream object to a stream in the Windows Runtime. You can also convert a stream in the Windows Runtime to a Stream object by using the AsStreamForRead and AsStreamForWrite methods. For more information, see How to: Convert Between .NET Framework Streams and Windows Runtime Streams

Some stream implementations perform local buffering of the underlying data to improve performance. For such streams, you can use the Flush or FlushAsync method to clear any internal buffers and ensure that all data has been written to the underlying data source or repository.

If you need a stream with no backing store (also known as a bit bucket), use the Null field to retrieve an instance of a stream that is designed for this purpose.

Notes to Inheritors

When you implement a derived class of Stream, you must provide implementations for the Read(Byte[], Int32, Int32) and Write(Byte[], Int32, Int32) methods. The asynchronous methods ReadAsync(Byte[], Int32, Int32), WriteAsync(Byte[], Int32, Int32), and CopyToAsync(Stream) use the synchronous methods Read(Byte[], Int32, Int32) and Write(Byte[], Int32, Int32) in their implementations. Therefore, your implementations of Read(Byte[], Int32, Int32) and Write(Byte[], Int32, Int32) will work correctly with the asynchronous methods. The default implementations of ReadByte() and WriteByte(Byte) create a new single-element byte array, and then call your implementations of Read(Byte[], Int32, Int32) and Write(Byte[], Int32, Int32). When you derive from Stream, we recommend that you override these methods to access your internal buffer, if you have one, for substantially better performance. You must also provide implementations of CanRead, CanSeek, CanWrite, Flush(), Length, Position, Seek(Int64, SeekOrigin), and SetLength(Int64).

Do not override the Close() method, instead, put all the Stream cleanup logic in the Dispose(Boolean) method. For more information, see Implementing a Dispose Method.

Applies to

.NET Framework: 4.8, 4.7.2, 4.7.1, 4.7, 4.6.2, 4.6.1, 4.6, 4.5.2, 4.5.1, 4.5, 4.0, 3.5, 3.0, 2.0, 1.1

See also

BufferedStream Class

Adds a buffering layer to read and write operations on another stream. This class cannot be inherited.

NamespaceSystem.IO AssembliesSystem.IO.dll, mscorlib.dll, netstandard.dll, System.Runtime.Extensions.dll
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class BufferedStream : System.IO.Stream

Inheritance: Object->MarshalByRefObject->->Stream->BufferedStream

Attributes: ComVisibleAttribute

Constructors

BufferedStream(Stream)

Initializes a new instance of the BufferedStream class with a default buffer size of 4096 bytes.

BufferedStream(Stream, Int32)

Initializes a new instance of the BufferedStream class with the specified buffer size.

Properties

CanRead

Gets a value indicating whether the current stream supports reading.

CanSeek

Gets a value indicating whether the current stream supports seeking.

CanTimeout

Gets a value that determines whether the current stream can time out.

(Inherited from Stream)
CanWrite

Gets a value indicating whether the current stream supports writing.

Length

Gets the stream length in bytes.

Position

Gets the position within the current stream.

ReadTimeout

Gets or sets a value, in milliseconds, that determines how long the stream will attempt to read before timing out.

(Inherited from Stream)
WriteTimeout

Gets or sets a value, in milliseconds, that determines how long the stream will attempt to write before timing out.

(Inherited from Stream)

Methods

BeginRead(Byte[], Int32, Int32, AsyncCallback, Object)

Begins an asynchronous read operation. (Consider using ReadAsync(Byte[], Int32, Int32, CancellationToken) instead.)

BeginWrite(Byte[], Int32, Int32, AsyncCallback, Object)

Begins an asynchronous write operation. (Consider using WriteAsync(Byte[], Int32, Int32, CancellationToken) instead.)

CopyTo(Stream)

Reads the bytes from the current stream and writes them to another stream.

(Inherited from Stream)
CopyToAsync(Stream)

Asynchronously reads the bytes from the current stream and writes them to another stream.

(Inherited from Stream)
CopyToAsync(Stream, Int32)

Asynchronously reads the bytes from the current stream and writes them to another stream, using a specified buffer size.

(Inherited from Stream)
CreateObjRef(Type)

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.

(Inherited from MarshalByRefObject)
CreateWaitHandle()

Allocates a WaitHandle object.

(Inherited from Stream)
Dispose()

Releases all resources used by the Stream.

(Inherited from Stream)
Dispose(Boolean)

Releases the unmanaged resources used by the Stream and optionally releases the managed resources.

(Inherited from Stream)
EndRead(IAsyncResult)

Waits for the pending asynchronous read operation to complete. (Consider using ReadAsync(Byte[], Int32, Int32, CancellationToken) instead.)

EndWrite(IAsyncResult)

Ends an asynchronous write operation and blocks until the I/O operation is complete. (Consider using WriteAsync(Byte[], Int32, Int32, CancellationToken) instead.)

Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
Flush()

Clears all buffers for this stream and causes any buffered data to be written to the underlying device.

FlushAsync()

Asynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device.

(Inherited from Stream)
FlushAsync(CancellationToken)

Asynchronously clears all buffers for this stream, causes any buffered data to be written to the underlying device, and monitors cancellation requests.

GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetLifetimeService()

Retrieves the current lifetime service object that controls the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
GetType()

Gets the Type of the current instance.

(Inherited from Object)
InitializeLifetimeService()

Obtains a lifetime service object to control the lifetime policy for this instance.

(Inherited from MarshalByRefObject)
MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
MemberwiseClone(Boolean)

Creates a shallow copy of the current MarshalByRefObject object.

(Inherited from MarshalByRefObject)
ObjectInvariant()

Provides support for a Contract.

(Inherited from Stream)
Read(Byte[], Int32, Int32)

Copies bytes from the current buffered stream to an array.

ReadAsync(Byte[], Int32, Int32)

Asynchronously reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.

(Inherited from Stream)
ReadAsync(Byte[], Int32, Int32, CancellationToken)

Asynchronously reads a sequence of bytes from the current stream, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

ReadByte()

Reads a byte from the underlying stream and returns the byte cast to an int, or returns -1 if reading from the end of the stream.

Seek(Int64, SeekOrigin)

Sets the position within the current buffered stream.

SetLength(Int64)

Sets the length of the buffered stream.

ToString()

Returns a string that represents the current object.

(Inherited from Object)
Write(Byte[], Int32, Int32)

Copies bytes to the buffered stream and advances the current position within the buffered stream by the number of bytes written.

WriteAsync(Byte[], Int32, Int32)

Asynchronously writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.

(Inherited from Stream)
WriteAsync(Byte[], Int32, Int32, CancellationToken)

Asynchronously writes a sequence of bytes to the current stream, advances the current position within this stream by the number of bytes written, and monitors cancellation requests.

WriteByte(Byte)

Writes a byte to the current position in the buffered stream.

Remarks

  • A buffer is a block of bytes in memory used to cache data, thereby reducing the number of calls to the operating system. Buffers improve read and write performance. A buffer can be used for either reading or writing, but never both simultaneously. The Read and Write methods of BufferedStream automatically maintain the buffer.

    Important

    This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic.

    BufferedStream can be composed around certain types of streams. It provides implementations for reading and writing bytes to an underlying data source or repository. Use BinaryReader and BinaryWriter for reading and writing other data types. BufferedStream is designed to prevent the buffer from slowing down input and output when the buffer is not needed. If you always read and write for sizes greater than the internal buffer size, then BufferedStream might not even allocate the internal buffer. BufferedStream also buffers reads and writes in a shared buffer. It is assumed that you will almost always be doing a series of reads or writes, but rarely alternate between the two of them.

Applies to

.NET Framework: 4.8, 4.7.2, 4.7.1, 4.7, 4.6.2, 4.6.1, 4.6, 4.5.2, 4.5.1, 4.5, 4.0, 3.5, 3.0, 2.0, 1.1

See also

 

Source/Reference


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References

  1. Active Server Pages,  , http://msdn.microsoft.com/en-us/library/aa286483.aspx
  2. ASP Overview,  , http://msdn.microsoft.com/en-us/library/ms524929%28v=vs.90%29.aspx
  3. ASP Best Practices,  , http://technet.microsoft.com/en-us/library/cc939157.aspx
  4. ASP Built-in Objects,  , http://msdn.microsoft.com/en-us/library/ie/ms524716(v=vs.90).aspx
  5. Response Object,  , http://msdn.microsoft.com/en-us/library/ms525405(v=vs.90).aspx
  6. Request Object,  , http://msdn.microsoft.com/en-us/library/ms524948(v=vs.90).aspx
  7. Server Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms525541(v=vs.90).aspx
  8. Application Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms525360(v=vs.90).aspx
  9. Session Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms524319(8v=vs.90).aspx
  10. ASPError Object,  , http://msdn.microsoft.com/en-us/library/ms524942(v=vs.90).aspx
  11. ObjectContext Object (IIS),  , http://msdn.microsoft.com/en-us/library/ms525667(v=vs.90).aspx
  12. Debugging Global.asa Files,  , http://msdn.microsoft.com/en-us/library/aa291249(v=vs.71).aspx
  13. How to: Debug Global.asa files,  , http://msdn.microsoft.com/en-us/library/ms241868(v=vs.80).aspx
  14. Calling COM Components from ASP Pages,  , http://msdn.microsoft.com/en-us/library/ms524620(v=VS.90).aspx
  15. IIS ASP Scripting Reference,  , http://msdn.microsoft.com/en-us/library/ms524664(v=vs.90).aspx
  16. ASP Keywords,  , http://msdn.microsoft.com/en-us/library/ms524672(v=vs.90).aspx
  17. Creating Simple ASP Pages,  , http://msdn.microsoft.com/en-us/library/ms524741(v=vs.90).aspx
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  20. FileSystemObject Object,  , http://msdn.microsoft.com/en-us/library/z9ty6h50(v=vs.84).aspx
  21. http://msdn.microsoft.com/en-us/library/windows/desktop/ms675944(v=vs.85).aspx,  , ADO Object Model
  22. ADO Fundamentals,  , http://msdn.microsoft.com/en-us/library/windows/desktop/ms680928(v=vs.85).aspx
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