System.IO.FileStream Class

public class FileStream : Stream

Base Types

Object
  MarshalByRefObject
    Stream
      FileStream

This type implements IDisposable.

Assembly

mscorlib

Library

BCL

Summary

Exposes a Stream around a file, supporting both synchronous and asynchronous read and write operations.

Description

FileStream is used for reading and writing files on a file system, as well as other file-related operating system handles such as pipes, standard input, standard output. FileStream buffers input and output for better performance.

The FileStream class can open a file in one of two modes, either synchronously or asynchronously, with significant performance consequences for the synchronous methods (System.IO.FileStream.Read(System.Byte[],System.Int32,System.Int32) and System.IO.FileStream.Write(System.Byte[],System.Int32,System.Int32)) and the asynchronous methods (System.IO.FileStream.BeginRead(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object) and System.IO.FileStream.BeginWrite(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object) ). Both sets of methods will work in either mode; however, the mode will affect the performance of these methods. FileStream defaults to opening files synchronously, but provides a constructor to open files asynchronously.

When accessing files, a security check is performed when the file is created or opened. The security check is typically not done again unless the file is closed and reopened. [Note: Checking permissions when the file is first accessed minimizes the impact of the security check on application performance (since opening a file happens once, while reading and writing can happen multiple times).]

Note that if an opened file is passed to an untrusted caller, the security system can, but is not required to prevent the caller from accessing the file.

FileStream objects support random access to files using the System.IO.FileStream.Seek(System.Int64,System.IO.SeekOrigin) method, and the System.IO.Stream.CanSeek properties of FileStream instances encapsulating files are set to true . The System.IO.FileStream.Seek(System.Int64,System.IO.SeekOrigin) method allows the read/write position to be moved to any position within the file. This is done with byte offset reference point parameters. The byte offset is relative to the seek reference point, which can be the beginning, the current position, or the end of the underlying file, as represented by the three values of the SeekOrigin enumeration.

If a FileStream encapsulates a device that does not support seeking, its System.IO.FileStream.CanSeek property is false . [Note: For additional information, see System.IO.Stream.CanSeek.]

[Note: The File class provides methods for the creation of FileStream objects based on file paths. The MemoryStream class creates a stream from a byte array and functions similarly to a FileStream.]

Example

The following example demonstrates the use of a FileStream object.

using System;
using System.IO;

class Directory {
   public static void Main(String[] args) { 
      FileStream fs = new FileStream("log.txt", FileMode.OpenOrCreate, FileAccess.Write);
      StreamWriter w = new StreamWriter(fs);         
      w.BaseStream.Seek(0, SeekOrigin.End);   // Set the file pointer to the end.

      Log ("Test1", w);
      Log ("Test2", w);
 
      w.Close(); // Close the writer and underlying file.     

      fs = new FileStream("log.txt", FileMode.OpenOrCreate, FileAccess.Read);

      StreamReader r = new StreamReader(fs);        
      r.BaseStream.Seek(0, SeekOrigin.Begin);   
      DumpLog (r);
   }

   public static void Log (String logMessage, StreamWriter w) {
      w.Write("Log Entry : ");
      w.WriteLine("{0} {1}", DateTime.Now.ToLongTimeString(), DateTime.Now.ToLongDateString());
      w.WriteLine(":");
      w.WriteLine(":{0}", logMessage);
      w.WriteLine ("-------------------------------");
      w.Flush();  
   }

   public static void DumpLog (StreamReader r) {
      while (r.Peek() > -1) { // While not at the end of the file, write to standard output.     
        Console.WriteLine(r.ReadLine());
      }

      r.Close();
   }
}

Some example output is

Log Entry : 9:26:21 AM Friday, July 06, 2001

:

:Test1

-------------------------------

Log Entry : 9:26:21 AM Friday, July 06, 2001

:

:Test2

-------------------------------

See Also

System.IO Namespace

Members

FileStream Constructors

FileStream(System.String, System.IO.FileMode) Constructor
FileStream(System.String, System.IO.FileMode, System.IO.FileAccess) Constructor
FileStream(System.String, System.IO.FileMode, System.IO.FileAccess, System.IO.FileShare) Constructor
FileStream(System.String, System.IO.FileMode, System.IO.FileAccess, System.IO.FileShare, int) Constructor
FileStream(System.String, System.IO.FileMode, System.IO.FileAccess, System.IO.FileShare, int, bool) Constructor

FileStream Methods

FileStream.BeginRead Method
FileStream.BeginWrite Method
FileStream.Close Method
FileStream.Dispose Method
FileStream.EndRead Method
FileStream.EndWrite Method
FileStream.Finalize Method
FileStream.Flush Method
FileStream.Read Method
FileStream.ReadByte Method
FileStream.Seek Method
FileStream.SetLength Method
FileStream.Write Method
FileStream.WriteByte Method

FileStream Properties

FileStream.CanRead Property
FileStream.CanSeek Property
FileStream.CanWrite Property
FileStream.IsAsync Property
FileStream.Length Property
FileStream.Position Property

Constructs and initializes a new instance of the FileStream class with the specified path and creation mode.

Parameters

path

A String containing the relative or absolute path for the file that the current FileStream object will encapsulate.

mode

A FileMode value that determines how to open or create the file.

Exceptions

Exception Type	Condition
ArgumentException	path is a zero-length string, contains only white space, or contains one or more implementation-defined invalid characters.
ArgumentNullException	path is null .
SecurityException	The caller does not have the required permission.
FileNotFoundException	mode is System.IO.FileMode.Truncate or System.IO.FileMode.Open, but the specified file cannot be found. If a different mode is specified and the file cannot be found, a new one is created.
IOException	An I/O error occurred, such as specifying System.IO.FileMode.CreateNew when the file specified by path already exists.
DirectoryNotFoundException	The directory information specified in path does not exist.
PathTooLongException	The length of path or the absolute path information for path exceeds the system-defined maximum length.
ArgumentOutOfRangeException	mode contains an invalid value.

Description

This constructor sets System.IO.FileAccess.ReadWrite access to the file, and the System.IO.Stream.CanRead and System.IO.Stream.CanWrite properties of the current instance are set to true .

[Note: path is not required to be a file stored on disk; it can be any part of a system that supports access via streams. For example, depending on the system, this class may be able to access a physical device.]

System.IO.Stream.CanSeek is true for all FileStream objects that encapsulate files. If path specifies a device that does not support seeking, the System.IO.FileStream.CanSeek property of the resulting FileStream is required to be false . [Note: For additional information, see System.IO.Stream.CanSeek . ]

Requests to open the file for writing by the current or another thread will fail until the FileStream object has been closed. Read attempts will succeed.

See Also

System.IO.FileStream Class, System.IO Namespace

Constructs and initializes a new instance of the FileStream class with the specified path, creation mode, and access type.

Parameters

path

A String containing the relative or absolute path for the file that the current FileStream object will encapsulate.

mode

A FileMode value that determines how to open or create the file.

access

A FileAccess value that determines how the file may be accessed by the FileStream object. This parameter is used to specify the initial values of the System.IO.FileStream.CanRead and System.IO.FileStream.CanWrite properties.

Exceptions

Exception Type	Condition
ArgumentNullException	path is null .
ArgumentException	path is a zero-length string, contains only white space, or contains one or more implementation-defined invalid characters.
FileNotFoundException	mode is System.IO.FileMode.Truncate or System.IO.FileMode.Open , but the specified file was not found. If a different mode is specified and the file was not found, a new one is created.
IOException	An I/O error occurred, such as specifying System.IO.FileMode.CreateNew when the file specified by path already exists.
SecurityException	The caller does not have the required permission.
DirectoryNotFoundException	The directory information specified by path does not exist.
UnauthorizedAccessException	The access requested is not permitted by the operating system for the specified path.
PathTooLongException	The length of path or the absolute path information for path exceeds the system-defined maximum length.
ArgumentOutOfRangeException	mode or access contain an invalid value.

Description

This constructor sets read/write access to the file. Requests to open the file for writing by the current or another thread will fail until the FileStream object has been closed. Read attempts will succeed.

[Note: path is not required to be a file stored on disk; it can be any part of a system that supports access via streams. For example, depending on the system, this class may be able to access a physical device.]

System.IO.Stream.CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the System.IO.FileStream.CanSeek property on the resulting FileStream is required to be false . For additional information, see System.IO.Stream.CanSeek .

See Also

System.IO.FileStream Class, System.IO Namespace

Constructs and initializes a new instance of the FileStream class with the specified path, creation mode, access type, and sharing permission.

Parameters

path

A String containing relative or absolute path for the file that the current FileStream object will encapsulate.

mode

A FileMode value that determines how to open or create the file.

access

A FileAccess value that determines how the file may be accessed by the FileStream object. This parameter is used to specify the initial values of the System.IO.FileStream.CanRead and System.IO.FileStream.CanWrite properties. For additional information, see System.IO.Stream.CanRead and System.IO.Stream.CanWrite.

share

A FileShare value that determines how the file will be shared by processes.

Exceptions

Exception Type	Condition
ArgumentNullException	path is null .
ArgumentException	path is a zero-length string, contains only white space, or contains one or more implementation-defined invalid characters.
FileNotFoundException	mode is System.IO.FileMode.Truncate or System.IO.FileMode.Open , but the specified file cannot be found. If a different mode is specified and the file cannot be found, a new one is created.
IOException	An I/O error occurred, such as specifying System.IO.FileMode.CreateNew and the file specified by path already exists.
SecurityException	The caller does not have the required permission.
DirectoryNotFoundException	The directory information specified by path does not exist.
UnauthorizedAccessException	The access requested is not permitted by the operating system for the specified path.
PathTooLongException	The length of path or the absolute path information for path exceeds the system-defined maximum length.
ArgumentOutOfRangeException	mode, access, or share contains an invalid value.

Description

This constructor sets read/write access to the file. Requests to open the file for writing by the current or another process will fail until the FileStream object has been closed. Read attempts will succeed.

[Note: path is not required to be a file stored on disk; it can be any part of a system that supports access via streams. For example, depending on the system, this class may be able to access a physical device.]

System.IO.Stream.CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the System.IO.FileStream.CanSeek property on the resulting FileStream is required to be false . For additional information, see System.IO.Stream.CanSeek .

See Also

System.IO.FileStream Class, System.IO Namespace

Constructs and initializes a new instance of the FileStream class.

Parameters

path

A String containing the relative or absolute path for the file that the current FileStream object will encapsulate.

mode

A FileMode constant that determines how to open or create the file.

access

A FileAccess value that determines how the file may be accessed by the FileStream object. This parameter is used to specify the initial values of the System.IO.FileStream.CanRead and System.IO.FileStream.CanWrite properties. For additional information, see System.IO.Stream.CanRead and System.IO.Stream.CanWrite .

share

A FileShare constant that determines how the file will be shared by processes.

bufferSize

A Int32 containing the desired buffer size in bytes.

Exceptions

Exception Type	Condition
ArgumentNullException	The path parameter is null .
ArgumentException	path is a zero-length string, contains only white space, or contains one or more implementation-defined invalid characters.
ArgumentOutOfRangeException	bufferSize is less than or equal to zero. -or- mode, access, or share contain an invalid value.
FileNotFoundException	mode is System.IO.FileMode.Truncate or System.IO.FileMode.Open , but the specified file cannot be found. If a different mode is specified and the file cannot be found, a new one is created.
IOException	An I/O error occurred, such as specifying System.IO.FileMode.CreateNew and the file specified by path already exists.
SecurityException	The caller does not have the required permission.
DirectoryNotFoundException	The directory information specified in path does not exist.
UnauthorizedAccessException	The access requested is not permitted by the operating system for the specified path.
PathTooLongException	The length of path or the absolute path information for path exceeds the system-defined maximum length.

Description

[Note: path is not required to be a file stored on disk; it can be any part of a system that supports access via streams. For example, depending on the system, this class may be able to access a physical device.]

System.IO.Stream.CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the System.IO.FileStream.CanSeek property on the resulting FileStream is required to be false . For additional information, see System.IO.Stream.CanSeek .

See Also

System.IO.FileStream Class, System.IO Namespace

Constructs and initializes a new instance of the FileStream class.

Parameters

path

A String containing the relative or absolute path for the file that the new FileStream object will encapsulate.

mode

A FileMode value that determines how to open or create the file.

access

A FileAccess value that determines how the file may be accessed by the FileStream object. This parameter is used to specify the initial values of the System.IO.FileStream.CanRead and System.IO.FileStream.CanWrite properties.

share

A FileShare value that determines how the file will be shared by processes.

bufferSize

A Int32 containing the desired buffer size in bytes.

useAsync

A Boolean value that specifies whether to use asynchronous I/O or synchronous I/O. If the underlying operating system does not support asynchronous I/O, the FileStream ignores this parameter and uses synchronous I/O.

Exceptions

Exception Type	Condition
ArgumentNullException	path is null .
ArgumentException	path is a zero-length string, contains only white space, or contains one or more implementation-defined invalid characters.
ArgumentOutOfRangeException	bufferSize is less than or equal to zero. -or- mode, access, or share contain an invalid value.
FileNotFoundException	mode is System.IO.FileMode.Truncate or System.IO.FileMode.Open, but the specified file cannot be found. If a different mode is specified and the file cannot be found, a new one is created.
IOException	An I/O error occurred, such as specifying System.IO.FileMode.CreateNew and the file specified by path already exists.
SecurityException	The caller does not have the required permission.
DirectoryNotFoundException	The directory information specified by path does not exist.
UnauthorizedAccessException	The access requested is not permitted by the operating system for the specified path.
PathTooLongException	The length of path or the absolute path information for path exceeds the system-defined maximum length.

Description

This constructor sets read/write access to the file. Requests to open the file for writing by this or another process will fail until the FileStream object has been closed. Read attempts will succeed.

[Note: path is not required to be a file stored on disk; it can be any part of a system that supports access via streams. For example, depending on the system, this class may be able to access a physical device.]

System.IO.Stream.CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the System.IO.FileStream.CanSeek property on the resulting FileStream is required to be false . For additional information, see System.IO.Stream.CanSeek .

See Also

System.IO.FileStream Class, System.IO Namespace

array

A Byte array that specifies the buffer to read data into.

offset

A Int32 containing the zero based byte offset in array at which to begin reading.

numBytes

A Int32 containing the maximum number of bytes to read.

userCallback

A AsyncCallback delegate that references the method to be called when the asynchronous read operation is completed.

stateObject

An application defined object containing the status of the asynchronous read.

Return Value

A IAsyncResult that references the asynchronous read.

Exceptions

Exception Type	Condition
ArgumentException	The sum of offset andnumBytes is greater than the length of array.
ArgumentNullException	array is null .
ArgumentOutOfRangeException	offset or numBytes is negative.
IOException	The asynchronous read operation attempted to read past the end of the file.

Description

To determine the number of bytes read, call System.IO.Stream.EndRead(System.IAsyncResult) with the returned IAsyncResult.

Multiple simultaneous asynchronous requests render the request completion order uncertain.

[Note: Use the System.IO.FileStream.CanRead property to determine whether the current instance supports reading. For additional information, see System.IO.Stream.CanRead.

This method overrides System.IO.Stream.BeginRead(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object).

]

See Also

System.IO.FileStream Class, System.IO Namespace

array

A Byte array buffer to write data to.

offset

A Int32 containing the zero based byte offset in array at which to begin writing.

numBytes

A Int32 containing the maximum number of bytes to write.

userCallback

A AsyncCallback delegate that references the method to be called when the asynchronous write operation is completed.

stateObject

An application defined object containing the status of the asynchronous read.

Return Value

A IAsyncResult that references the asynchronous write.

Exceptions

Exception Type	Condition
ArgumentException	The sum of offset and numBytes is greater than the length of array.
ArgumentNullException	array is null .
ArgumentOutOfRangeException	offset or numBytes is negative.
IOException	The stream does not support writing, or an I/O error occurred.

Description

Multiple simultaneous asynchronous requests render the request completion order uncertain.

[Note: Use the System.IO.FileStream.CanWrite property to determine whether the current instance supports writing. For additional information, see System.IO.Stream.CanWrite.

This method overrides System.IO.Stream.BeginWrite(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object).

]

See Also

System.IO.FileStream Class, System.IO Namespace

This method is equivalent to System.IO.FileStream.Dispose(System.Boolean)(true ).

Any data previously written to the buffer is copied to the file before the file stream is closed, so it is not necessary to call System.IO.FileStream.Flush before invoking Close . Following a call to Close , any operations on the file stream might raise exceptions. Invoking this method on the same instance multiple times does not result in an exception.

[Usage: The System.IO.FileStream.Finalize method invokes Close so that the file stream is closed before the garbage collector finalizes the object. However, objects writing to the FileStream, such as a StreamWriter, might not have flushed the data from their internal buffers to the FileStream when the call to Finalize closes the stream. To prevent data loss, always call Close on the highest-level object.]

[Note: This method overrides System.IO.Stream.Close. ]

See Also

System.IO.FileStream Class, System.IO Namespace

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

Parameters

disposing

Specify true to release both managed and unmanaged resources, or specify false to release only unmanaged resources.

Exceptions

Exception Type	Condition
IOException	An I/O error occurred.

Description

When the disposing parameter is true , this method releases all resources held by any managed objects that this FileStream references.

[Note: System.IO.FileStream.Dispose(System.Boolean) may be called multiple times by other objects. When overriding System.IO.FileStream.Dispose(System.Boolean)(Boolean), be careful not to reference objects that have been previously disposed in an earlier call to System.IO.FileStream.Dispose(System.Boolean) .

]

See Also

System.IO.FileStream Class, System.IO Namespace

asyncResult

The IAsyncResult object for the pending asynchronous request.

Return Value

A Int32 containing the number of bytes read from the stream. Returns 0 only if the end of the file has been reached, otherwise, this method blocks until at least one byte is available.

Exceptions

Exception Type	Condition
ArgumentNullException	asyncResult is null .
ArgumentException	asyncResult was not returned by a call to System.IO.FileStream.BeginRead(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object).
InvalidOperationException	System.IO.FileStream.EndRead(System.IAsyncResult) was called multiple times with asyncResult .

Description

EndRead will block until the I/O operation has completed.

[Note: This method overrides System.IO.Stream.EndRead(System.IAsyncResult).]

See Also

System.IO.FileStream Class, System.IO Namespace

asyncResult

The IAsyncResult object for the pending asynchronous request.

Exceptions

Exception Type	Condition
ArgumentNullException	asyncResult is null .
ArgumentException	asyncResult was not returned by a call to System.IO.FileStream.BeginWrite(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object).
InvalidOperationException	System.IO.FileStream.EndWrite(System.IAsyncResult) was called multiple times with asyncResult .

Description

System.IO.FileStream.EndWrite(System.IAsyncResult) will block until the I/O operation has completed.

[Note: This method overrides System.IO.Stream.EndWrite(System.IAsyncResult).]

See Also

System.IO.FileStream Class, System.IO Namespace

System.IO.FileStream.Finalize closes the FileStream.

[Note: Application code does not call this method; it is automatically invoked by during garbage collection unless finalization by the garbage collector has been disabled. For more information, see System.GC.SuppressFinalize(System.Object), and System.Object.Finalize.

This method overrides System.Object.Finalize.

]

See Also

System.IO.FileStream Class, System.IO Namespace

A FileStream buffer can be used either for reading or writing. If data was copied to the buffer for writing, it is written to the file and the buffer is cleared.

If data was copied to the buffer for reading, and the System.IO.Stream.CanSeek property is true , the current position within the file is decremented by the number of unread bytes in the buffer. The buffer is then cleared.

[Note: This method overrides System.IO.Stream.Flush.]

See Also

System.IO.FileStream Class, System.IO Namespace

array

A Byte array. When this method returns, the bytes between offset and (offset + count - 1) in array are replaced by the bytes read from the current stream.

offset

A Int32 containing the byte offset in array at which to begin writing data read from the current stream.

count

A Int32 containing maximum number of bytes to read.

Return Value

A Int32 containing the total number of bytes read into the buffer, or zero if the end of the stream is reached.

Exceptions

Exception Type	Condition
ArgumentNullException	array is null .
ArgumentOutOfRangeException	offset or count is negative.
NotSupportedException	The current stream does not support reading.
IOException	An I/O error occurred.
ArgumentException	offset + count is greater than the length of array.
ObjectDisposedException	The current stream is closed.

Description

The System.IO.FileStream.Read(System.Byte[],System.Int32,System.Int32) method returns zero only after reaching the end of the stream. Otherwise, System.IO.FileStream.Read(System.Byte[],System.Int32,System.Int32) always reads at least one byte from the stream before returning. If no data is available from the stream, this method blocks until at least one byte of data can be returned.

If the read operation is successful, the current position of the stream is advanced by the number of bytes read. If an exception occurs, the current position of the stream is unchanged.

[Note: Use the System.IO.FileStream.CanRead property to determine whether the current instance supports reading. For additional information, see System.IO.Stream.CanRead.]

[Note: This method overrides System.IO.Stream.Read(System.Byte[],System.Int32,System.Int32) .]

See Also

System.IO.FileStream Class, System.IO Namespace

The byte cast to a Int32, or -1 if the end of the stream has been reached.

Exceptions

Exception Type	Condition
ObjectDisposedException	The current stream is closed.
NotSupportedException	The current stream does not support reading.

Description

[Note: Use the System.IO.FileStream.CanRead property to determine whether the current instance supports reading. For additional information, see System.IO.Stream.CanRead.

This method overrides System.IO.Stream.ReadByte.

]

See Also

System.IO.FileStream Class, System.IO Namespace

offset

A Int64 containing the position relative to origin from which to begin seeking.

origin

A SeekOrigin value specifying the beginning, the end, or the current position as a reference point for offset.

Return Value

A Int64 containing the new position in the stream.

Exceptions

Exception Type	Condition
IOException	An I/O error occurred.
NotSupportedException	The stream does not support seeking.
ArgumentException	Attempted seeking before the beginning of the stream or to more than one byte past the end of the stream.
ObjectDisposedException	The current stream is closed.

Description

[Note: Use the System.IO.FileStream.CanSeek property to determine whether the current instance supports seeking. For additional information, see System.IO.Stream.CanSeek .]

[Usage: In order to open a new file and write to it, set the position to one byte beyond the end of the stream. This allows you to append to the file. The position cannot be set to more than one byte beyond the end of the stream.]

[Note: This method overrides System.IO.Stream.Seek(System.Int64,System.IO.SeekOrigin).]

See Also

System.IO.FileStream Class, System.IO Namespace

value

A Int64 that specifies the new length of the stream.

Exceptions

Exception Type	Condition
IOException	An I/O error occurred.
NotSupportedException	The current stream does not support writing and seeking.
ArgumentOutOfRangeException	value is less than zero.

Description

If value is less than the current length of the stream, the stream is truncated. If value is greater than the current length of the stream, the stream is expanded, and the contents of the stream between the old and the new length are undefined. A stream is required to support both writing and seeking to implement System.IO.FileStream.SetLength(System.Int64).

[Note: Use the System.IO.FileStream.CanWrite property to determine whether the current instance supports writing, and the System.IO.FileStream.CanSeek property to determine whether seeking is supported. For additional information, see System.IO.Stream.CanWrite and System.IO.Stream.CanSeek .

This method overrides System.IO.Stream.SetLength(System.Int64).

]

See Also

System.IO.FileStream Class, System.IO Namespace

array

The Byte array to read.

offset

A Int32 that specifies the byte offset in array at which to begin reading.

count

A Int32 that specifies the maximum number of bytes to write to the current stream.

Exceptions

Exception Type	Condition
ArgumentNullException	array is null .
ArgumentException	offset + count is greater than the length of array.
ArgumentOutOfRangeException	offset or count is negative.
IOException	An I/O error occurred.
NotSupportedException	The current stream does not support writing.

Description

If the write operation is successful, the current position of the stream is advanced by the number of bytes written. If an exception occurs, the current position of the stream is unchanged.

[Note: Use the System.IO.FileStream.CanWrite property to determine whether the current instance supports writing. For additional information, see System.IO.Stream.CanWrite.

This method overrides System.IO.Stream.Write(System.Byte[],System.Int32,System.Int32).

]

See Also

System.IO.FileStream Class, System.IO Namespace

value

A Byte to write to the stream.

Exceptions

Exception Type	Condition
IOException	The current stream is closed.
NotSupportedException	The current stream does not support writing.

Description

[Usage: Use System.IO.FileStream.WriteByte(System.Byte) method to write a byte to a FileStream efficiently.]

[Note: Use the System.IO.FileStream.CanWrite property to determine whether the current instance supports writing. For additional information, see System.IO.Stream.CanWrite.

This method overrides System.IO.Stream.WriteByte(System.Byte).

]

See Also

System.IO.FileStream Class, System.IO Namespace

Gets a Boolean value indicating whether the current stream supports reading.

Property Value

true if the stream supports reading; false if the stream is closed or was opened with write-only access.

Description

This property is read-only.

[Note: This property overrides System.IO.Stream.CanRead.

If a class derived from Stream does not support reading, the Read and Peek methods throw a NotSupportedException .

]

See Also

System.IO.FileStream Class, System.IO Namespace

Gets a Boolean value indicating whether the current stream supports seeking.

Property Value

true if the stream supports seeking; false if the stream is closed or if the FileStream was constructed from an operating-system handle such as a pipe or output to the console.

Description

[Note: If a class derived from Stream does not support seeking, a call to System.IO.FileStream.Length (both get and set ), System.IO.FileStream.Position, or System.IO.FileStream.Seek(System.Int64,System.IO.SeekOrigin) throws a NotSupportedException .

This property overrides System.IO.Stream.CanSeek.

]

See Also

System.IO.FileStream Class, System.IO Namespace

Gets a Boolean value indicating whether the current stream supports writing.

Property Value

true if the stream supports writing; false if the stream is closed or was opened with read-only access.

Description

If a class derived from Stream does not support writing, a call to System.IO.FileStream.Write(System.Byte[],System.Int32,System.Int32), System.IO.FileStream.BeginWrite(System.Byte[],System.Int32,System.Int32,System.AsyncCallback,System.Object), or System.IO.FileStream.EndWrite(System.IAsyncResult) will throw a NotSupportedException .

[Note: This property overrides System.IO.Stream.CanWrite.]

See Also

System.IO.FileStream Class, System.IO Namespace

Gets a Boolean value indicating whether the current instance was opened asynchronously or synchronously.

Property Value

true if the current FileStream was opened asynchronously; otherwise, false .

Description

[Behaviors: This property is read-only.]

See Also

System.IO.FileStream Class, System.IO Namespace

A Int64 value containing the length of the stream in bytes.

Exceptions

Exception Type	Condition
NotSupportedException	System.IO.FileStream.CanSeek for this stream is false .
IOException	An I/O error occurred, such as the file being closed.

Description

This property is read-only.

See Also

System.IO.FileStream Class, System.IO Namespace

A Int64 containing the current position of this stream.

Exceptions

Exception Type	Condition
NotSupportedException	The current stream does not support seeking.
IOException	An I/O error occurred.
EndOfStreamException	Attempted seeking past the end of a stream that does not support this.
ArgumentOutOfRangeException	The value specified for a set operation is negative.

Description

In order to open a new file and write to it, set the position to one byte beyond the end of the stream. This allows you to append to the file. The position cannot be set to more than one byte beyond the end of the stream.

See Also

System.IO.FileStream Class, System.IO Namespace