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UnmanagedMemoryStream Class
 

Provides access to unmanaged blocks of memory from managed code.

Namespace:   System.IO
Assembly:  mscorlib (in mscorlib.dll)

Inheritance Hierarchy
SystemObject
   SystemMarshalByRefObject
     System.IOStream
      System.IOUnmanagedMemoryStream
         System.IO.MemoryMappedFilesMemoryMappedViewStream

Syntax
public class UnmanagedMemoryStream : Stream
public ref class UnmanagedMemoryStream : Stream
type UnmanagedMemoryStream = 
    class
        inherit Stream
    end
Public Class UnmanagedMemoryStream
	Inherits Stream
Constructors
NameDescription
System_CAPS_protmethod UnmanagedMemoryStream

Initializes a new instance of the UnmanagedMemoryStream class.

System_CAPS_pubmethod UnmanagedMemoryStream

Initializes a new instance of the UnmanagedMemoryStream class using the specified location and memory length.

System_CAPS_pubmethod UnmanagedMemoryStream

Initializes a new instance of the UnmanagedMemoryStream class using the specified location, memory length, total amount of memory, and file access values.

System_CAPS_pubmethod UnmanagedMemoryStream

Initializes a new instance of the UnmanagedMemoryStream class in a safe buffer with a specified offset and length.

System_CAPS_pubmethod UnmanagedMemoryStream

Initializes a new instance of the UnmanagedMemoryStream class in a safe buffer with a specified offset, length, and file access.

Properties
NameDescription
System_CAPS_pubproperty

Gets a value indicating whether a stream supports reading.(Overrides .)

System_CAPS_pubproperty

Gets a value indicating whether a stream supports seeking.(Overrides .)

System_CAPS_pubproperty

Gets a value that determines whether the current stream can time out.(Inherited from Stream.)

System_CAPS_pubproperty

Gets a value indicating whether a stream supports writing.(Overrides .)

System_CAPS_pubproperty

Gets the stream length (size) or the total amount of memory assigned to a stream (capacity).

System_CAPS_pubproperty

Gets the length of the data in a stream.(Overrides .)

System_CAPS_pubproperty

Gets or sets the current position in a stream.(Overrides .)

System_CAPS_pubproperty

Gets or sets a byte pointer to a stream based on the current position in the stream.

System_CAPS_pubproperty

Gets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream.)

System_CAPS_pubproperty

Gets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream.)

Methods
NameDescription
System_CAPS_pubmethod BeginRead

Begins an asynchronous read operation. (Consider using ReadAsync instead; see the Remarks section.)(Inherited from Stream.)

System_CAPS_pubmethod BeginWrite

Begins an asynchronous write operation. (Consider using WriteAsync instead; see the Remarks section.)(Inherited from Stream.)

System_CAPS_pubmethod 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.(Inherited from Stream.)

System_CAPS_pubmethod CopyTo

Reads the bytes from the current stream and writes them to another stream.(Inherited from Stream.)

System_CAPS_pubmethod CopyTo

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

System_CAPS_pubmethod CopyToAsync

Asynchronously reads the bytes from the current stream and writes them to another stream.(Inherited from Stream.)

System_CAPS_pubmethod CopyToAsync

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

System_CAPS_pubmethod CopyToAsync

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

System_CAPS_pubmethod CreateObjRef

Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.(Inherited from MarshalByRefObject.)

System_CAPS_protmethod CreateWaitHandle

Obsolete.Allocates a WaitHandle object.(Inherited from Stream.)

System_CAPS_pubmethod Dispose

Releases all resources used by the Stream.(Inherited from Stream.)

System_CAPS_protmethod Dispose

Releases the unmanaged resources used by the UnmanagedMemoryStream and optionally releases the managed resources.(Overrides StreamDispose.)

System_CAPS_pubmethod EndRead

Waits for the pending asynchronous read to complete. (Consider using ReadAsync instead; see the Remarks section.)(Inherited from Stream.)

System_CAPS_pubmethod EndWrite

Ends an asynchronous write operation. (Consider using WriteAsync instead; see the Remarks section.)(Inherited from Stream.)

System_CAPS_pubmethod Equals

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethod Finalize

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethod Flush

Overrides the Flush method so that no action is performed.(Overrides StreamFlush.)

System_CAPS_pubmethod FlushAsync

Asynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device.(Inherited from Stream.)

System_CAPS_pubmethod FlushAsync

Overrides the StreamFlushAsync method so that the operation is cancelled if specified, but no other action is performed.

Available starting in .NET Framework 4.6(Overrides StreamFlushAsync.)

System_CAPS_pubmethod GetHashCode

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethod GetLifetimeService

Retrieves the current lifetime service object that controls the lifetime policy for this instance.(Inherited from MarshalByRefObject.)

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethod Initialize

Initializes a new instance of the UnmanagedMemoryStream class by using a pointer to an unmanaged memory location.

System_CAPS_protmethod Initialize

Initializes a new instance of the UnmanagedMemoryStream class in a safe buffer with a specified offset, length, and file access.

System_CAPS_pubmethod InitializeLifetimeService

Obtains a lifetime service object to control the lifetime policy for this instance.(Inherited from MarshalByRefObject.)

System_CAPS_protmethod MemberwiseClone

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_protmethod MemberwiseClone

Creates a shallow copy of the current MarshalByRefObject object.(Inherited from MarshalByRefObject.)

System_CAPS_protmethod ObjectInvariant

Obsolete. This API supports the product infrastructure and is not intended to be used directly from your code. Provides support for a Contract.(Inherited from Stream.)

System_CAPS_pubmethod Read

Reads the specified number of bytes into the specified array.(Overrides StreamRead.)

System_CAPS_pubmethod ReadAsync

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.)

System_CAPS_pubmethod ReadAsync

Asynchronously reads the specified number of bytes into the specified array.

Available starting in .NET Framework 4.6(Overrides StreamReadAsync.)

System_CAPS_pubmethod ReadByte

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

System_CAPS_pubmethod Seek

Sets the current position of the current stream to the given value.(Overrides StreamSeek.)

System_CAPS_pubmethod SetLength

Sets the length of a stream to a specified value.(Overrides StreamSetLength.)

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubmethod Write

Writes a block of bytes to the current stream using data from a buffer.(Overrides StreamWrite.)

System_CAPS_pubmethod WriteAsync

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.)

System_CAPS_pubmethod WriteAsync

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.

Available starting in .NET Framework 4.6(Overrides StreamWriteAsync.)

System_CAPS_pubmethod WriteByte

Writes a byte to the current position in the file stream.(Overrides StreamWriteByte.)

Remarks

This class supports access to unmanaged memory using the existing stream-based model and does not require that the contents in the unmanaged memory be copied to the heap.

System_CAPS_importantImportant

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.

Examples

The following code example demonstrates how to read from and write to unmanaged memory using the UnmanagedMemoryStream class. A block of unmanaged memory is allocated and de-allocated using the Marshal class.


// Note: you must compile this sample using the unsafe flag.
// From the command line, type the following: csc sample.cs /unsafe

using System;
using System.IO;
using System.Text;
using System.Runtime.InteropServices;

unsafe class TestWriter
{

    static void Main()
	{

            // Create some data to read and write.
            byte[] message = UnicodeEncoding.Unicode.GetBytes("Here is some data.");

	    // Allocate a block of unmanaged memory and return an IntPtr object.	
            IntPtr memIntPtr = Marshal.AllocHGlobal(message.Length);

            // Get a byte pointer from the IntPtr object.
            byte* memBytePtr = (byte*) memIntPtr.ToPointer();

            // Create an UnmanagedMemoryStream object using a pointer to unmanaged memory.
            UnmanagedMemoryStream writeStream = new UnmanagedMemoryStream(memBytePtr, message.Length, message.Length, FileAccess.Write);

            // Write the data.
            writeStream.Write(message, 0, message.Length);

            // Close the stream.
            writeStream.Close();

            // Create another UnmanagedMemoryStream object using a pointer to unmanaged memory.
            UnmanagedMemoryStream readStream = new UnmanagedMemoryStream(memBytePtr, message.Length, message.Length, FileAccess.Read);

	    // Create a byte array to hold data from unmanaged memory.
            byte[] outMessage = new byte[message.Length];

            // Read from unmanaged memory to the byte array.
            readStream.Read(outMessage, 0, message.Length);

            // Close the stream.
            readStream.Close();

            // Display the data to the console.
            Console.WriteLine(UnicodeEncoding.Unicode.GetString(outMessage));

            // Free the block of unmanaged memory.
            Marshal.FreeHGlobal(memIntPtr);

            Console.ReadLine();
    }
}
Version Information
Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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