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.NET Framework Class Library
MemoryStream Class

Creates a stream whose backing store is memory.

To browse the .NET Framework source code for this type, see the Reference Source.

Namespace:   System.IO
Assemblies:   mscorlib (in mscorlib.dll)
  System.IO (in System.IO.dll)
Syntax
<[%$TOPIC/9a84386f_en-us_VS_110_3_0_0_0_0%]> _
<[%$TOPIC/9a84386f_en-us_VS_110_3_0_0_0_1%](True)> _
Public Class MemoryStream _
	Inherits [%$TOPIC/9a84386f_en-us_VS_110_3_0_0_0_2%]
[[%$TOPIC/9a84386f_en-us_VS_110_3_0_1_0_0%]]
[[%$TOPIC/9a84386f_en-us_VS_110_3_0_1_0_1%](true)]
public class MemoryStream : [%$TOPIC/9a84386f_en-us_VS_110_3_0_1_0_2%]
[[%$TOPIC/9a84386f_en-us_VS_110_3_0_2_0_0%]]
[[%$TOPIC/9a84386f_en-us_VS_110_3_0_2_0_1%](true)]
public ref class MemoryStream : public [%$TOPIC/9a84386f_en-us_VS_110_3_0_2_0_2%]
[<[%$TOPIC/9a84386f_en-us_VS_110_3_0_3_0_0%]>]
[<[%$TOPIC/9a84386f_en-us_VS_110_3_0_3_0_1%](true)>]
type MemoryStream =  
    class 
        inherit [%$TOPIC/9a84386f_en-us_VS_110_3_0_3_0_2%] 
    end
public class MemoryStream extends [%$TOPIC/9a84386f_en-us_VS_110_3_0_4_0_0%]

The MemoryStream type exposes the following members.

Constructors
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library MemoryStreamInitializes a new instance of the MemoryStream class with an expandable capacity initialized to zero.
Public method Supported by the XNA Framework Supported by Portable Class Library MemoryStream(Byte)Initializes a new non-resizable instance of the MemoryStream class based on the specified byte array.
Public method Supported by the XNA Framework Supported by Portable Class Library MemoryStream(Int32)Initializes a new instance of the MemoryStream class with an expandable capacity initialized as specified.
Public method Supported by the XNA Framework Supported by Portable Class Library MemoryStream(Byte, Boolean)Initializes a new non-resizable instance of the MemoryStream class based on the specified byte array with the CanWrite property set as specified.
Public method Supported by the XNA Framework Supported by Portable Class Library MemoryStream(Byte, Int32, Int32)Initializes a new non-resizable instance of the MemoryStream class based on the specified region (index) of a byte array.
Public method Supported by the XNA Framework Supported by Portable Class Library MemoryStream(Byte, Int32, Int32, Boolean)Initializes a new non-resizable instance of the MemoryStream class based on the specified region of a byte array, with the CanWrite property set as specified.
Public method Supported by the XNA Framework MemoryStream(Byte, Int32, Int32, Boolean, Boolean)Initializes a new instance of the MemoryStream class based on the specified region of a byte array, with the CanWrite property set as specified, and the ability to call GetBuffer set as specified.
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Properties
  NameDescription
Public property Supported by the XNA Framework Supported by Portable Class Library CanReadGets a value indicating whether the current stream supports reading. (Overrides StreamCanRead.)
Public property Supported by the XNA Framework Supported by Portable Class Library CanSeekGets a value indicating whether the current stream supports seeking. (Overrides StreamCanSeek.)
Public property Supported by the XNA Framework Supported by Portable Class Library CanTimeoutGets a value that determines whether the current stream can time out. (Inherited from Stream.)
Public property Supported by the XNA Framework Supported by Portable Class Library CanWriteGets a value indicating whether the current stream supports writing. (Overrides StreamCanWrite.)
Public property Supported by the XNA Framework Supported by Portable Class Library CapacityGets or sets the number of bytes allocated for this stream.
Public property Supported by the XNA Framework Supported by Portable Class Library LengthGets the length of the stream in bytes. (Overrides StreamLength.)
Public property Supported by the XNA Framework Supported by Portable Class Library PositionGets or sets the current position within the stream. (Overrides StreamPosition.)
Public property Supported by the XNA Framework Supported by Portable Class Library ReadTimeoutGets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream.)
Public property Supported by the XNA Framework Supported by Portable Class Library WriteTimeoutGets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream.)
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Methods
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library BeginReadBegins an asynchronous read operation. (Consider using ReadAsync instead; see the Remarks section.) (Inherited from Stream.)
Public method Supported by the XNA Framework Supported by Portable Class Library BeginWriteBegins an asynchronous write operation. (Consider using WriteAsync instead; see the Remarks section.) (Inherited from Stream.)
Public method Supported by the XNA Framework CloseCloses 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.)
Public method Supported by Portable Class Library CopyTo(Stream)Reads the bytes from the current stream and writes them to another stream. (Inherited from Stream.)
Public method Supported by Portable Class Library CopyTo(Stream, Int32)Reads the bytes from the current stream and writes them to another stream, using a specified buffer size. (Inherited from Stream.)
Public method CopyToAsync(Stream)Asynchronously reads the bytes from the current stream and writes them to another stream. (Inherited from Stream.)
Public method 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.)
Public method CopyToAsync(Stream, Int32, CancellationToken)Asynchronously reads all the bytes from the current stream and writes them to another stream, using a specified buffer size and cancellation token. (Overrides StreamCopyToAsync(Stream, Int32, CancellationToken).)
Public method CreateObjRefCreates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Protected method Supported by the XNA Framework CreateWaitHandleObsolete. Allocates a WaitHandle object. (Inherited from Stream.)
Public method Supported by the XNA Framework Supported by Portable Class Library DisposeReleases all resources used by the Stream. (Inherited from Stream.)
Protected method Supported by the XNA Framework Supported by Portable Class Library Dispose(Boolean)Releases the unmanaged resources used by the MemoryStream class and optionally releases the managed resources. (Overrides StreamDispose(Boolean).)
Public method Supported by the XNA Framework Supported by Portable Class Library EndReadWaits for the pending asynchronous read to complete. (Consider using ReadAsync instead; see the Remarks section.) (Inherited from Stream.)
Public method Supported by the XNA Framework Supported by Portable Class Library EndWriteEnds an asynchronous write operation. (Consider using WriteAsync instead; see the Remarks section.) (Inherited from Stream.)
Public method Supported by the XNA Framework Supported by Portable Class Library Equals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected method Supported by the XNA Framework Supported by Portable Class Library FinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method Supported by the XNA Framework Supported by Portable Class Library FlushOverrides the StreamFlush method so that no action is performed. (Overrides StreamFlush.)
Public method FlushAsyncAsynchronously clears all buffers for this stream and causes any buffered data to be written to the underlying device. (Inherited from Stream.)
Public method FlushAsync(CancellationToken)Asynchronously clears all buffers for this stream, and monitors cancellation requests. (Overrides StreamFlushAsync(CancellationToken).)
Public method Supported by the XNA Framework GetBufferReturns the array of unsigned bytes from which this stream was created.
Public method Supported by the XNA Framework Supported by Portable Class Library GetHashCodeServes as the default hash function. (Inherited from Object.)
Public method GetLifetimeServiceRetrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public method Supported by the XNA Framework Supported by Portable Class Library GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method InitializeLifetimeServiceObtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected method Supported by the XNA Framework Supported by Portable Class Library MemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected method MemberwiseClone(Boolean)Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Protected method ObjectInvariantInfrastructure. Obsolete. Provides support for a Contract. (Inherited from Stream.)

In .NET Framework Client Profile, this member is overridden by ObjectInvariant.
Public method Supported by the XNA Framework Supported by Portable Class Library ReadReads a block of bytes from the current stream and writes the data to a buffer. (Overrides StreamRead(Byte, Int32, Int32).)
Public method 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.)
Public method 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. (Overrides StreamReadAsync(Byte, Int32, Int32, CancellationToken).)
Public method Supported by the XNA Framework Supported by Portable Class Library ReadByteReads a byte from the current stream. (Overrides StreamReadByte.)
Public method Supported by the XNA Framework Supported by Portable Class Library SeekSets the position within the current stream to the specified value. (Overrides StreamSeek(Int64, SeekOrigin).)
Public method Supported by the XNA Framework Supported by Portable Class Library SetLengthSets the length of the current stream to the specified value. (Overrides StreamSetLength(Int64).)
Public method Supported by the XNA Framework Supported by Portable Class Library ToArrayWrites the stream contents to a byte array, regardless of the Position property.
Public method Supported by the XNA Framework Supported by Portable Class Library ToStringReturns a string that represents the current object. (Inherited from Object.)
Public method TryGetBufferReturns the array of unsigned bytes from which this stream was created. The return value indicates whether the conversion succeeded.
Public method Supported by the XNA Framework Supported by Portable Class Library WriteWrites a block of bytes to the current stream using data read from a buffer. (Overrides StreamWrite(Byte, Int32, Int32).)
Public method 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.)
Public method 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. (Overrides StreamWriteAsync(Byte, Int32, Int32, CancellationToken).)
Public method Supported by the XNA Framework Supported by Portable Class Library WriteByteWrites a byte to the current stream at the current position. (Overrides StreamWriteByte(Byte).)
Public method Supported by the XNA Framework Supported by Portable Class Library WriteToWrites the entire contents of this memory stream to another stream.
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Extension Methods
  NameDescription
Public Extension Method AsInputStreamConverts a managed stream in the .NET for Windows Store apps to an input stream in the Windows Runtime. (Defined by WindowsRuntimeStreamExtensions.)
Public Extension Method AsOutputStreamConverts a managed stream in the .NET for Windows Store apps to an output stream in the Windows Runtime. (Defined by WindowsRuntimeStreamExtensions.)
Public Extension Method AsRandomAccessStreamConverts the specified stream to a random access stream. (Defined by WindowsRuntimeStreamExtensions.)
Public Extension Method GetWindowsRuntimeBufferOverloaded. Returns a Windows.Storage.Streams.IBuffer interface that represents the same memory as the specified memory stream. (Defined by WindowsRuntimeBufferExtensions.)
Public Extension Method GetWindowsRuntimeBuffer(Int32, Int32)Overloaded. Returns a Windows.Storage.Streams.IBuffer interface that represents a region within the memory that the specified memory stream represents. (Defined by WindowsRuntimeBufferExtensions.)
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Remarks
NoteNote

To view the .NET Framework source code for this type, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions.

The current position of a stream is the position at which the next read or write operation could take place. The current position can be retrieved or set through the Seek method. When a new instance of MemoryStream is created, the current position is set to zero.

Important noteImportant

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.

Memory streams created with an unsigned byte array provide a non-resizable stream of the data. When using a byte array, you can neither append to nor shrink the stream, although you might be able to modify the existing contents depending on the parameters passed into the constructor. Empty memory streams are resizable, and can be written to and read from.

If a MemoryStream object is added to a ResX file or a .resources file, call the GetStream method at runtime to retrieve it.

If a MemoryStream object is serialized to a resource file it will actually be serialized as an UnmanagedMemoryStream. This behavior provides better performance, as well as the ability to get a pointer to the data directly, without having to go through Stream methods.

Examples

The following code example shows how to read and write data using memory as a backing store.

Imports System
Imports System.IO
Imports System.Text

Module MemStream

    Sub Main()

        Dim count As Integer 
        Dim byteArray As Byte()
        Dim charArray As Char()
        Dim uniEncoding As New UnicodeEncoding()

        ' Create the data to write to the stream. 
        Dim firstString As Byte() = _
            uniEncoding.GetBytes("Invalid file path characters are: ")
        Dim secondString As Byte() = _
            uniEncoding.GetBytes(Path.GetInvalidPathChars())

        Dim memStream As New MemoryStream(100)
        Try 
            ' Write the first string to the stream.
            memStream.Write(firstString, 0 , firstString.Length)

            ' Write the second string to the stream, byte by byte.
            count = 0
            While(count < secondString.Length)
                memStream.WriteByte(secondString(count))
                count += 1
            End While 

            ' Write the stream properties to the console.
            Console.WriteLine( _
                "Capacity = {0}, Length = {1}, Position = {2}", _
                memStream.Capacity.ToString(), _
                memStream.Length.ToString(), _
                memStream.Position.ToString())

            ' Set the stream position to the beginning of the stream.
            memStream.Seek(0, SeekOrigin.Begin)

            ' Read the first 20 bytes from the stream.
            byteArray = _
                New Byte(CType(memStream.Length, Integer)){}
            count = memStream.Read(byteArray, 0, 20)

            ' Read the remaining Bytes, Byte by Byte. 
            While(count < memStream.Length)
                byteArray(count) = _
                    Convert.ToByte(memStream.ReadByte())
                count += 1
            End While 

            ' Decode the Byte array into a Char array  
            ' and write it to the console.
            charArray = _
                New Char(uniEncoding.GetCharCount( _
                byteArray, 0, count)){}
            uniEncoding.GetDecoder().GetChars( _
                byteArray, 0, count, charArray, 0)
            Console.WriteLine(charArray)
        Finally
            memStream.Close()
        End Try 

    End Sub 
End Module
using System;
using System.IO;
using System.Text;

class MemStream
{
    static void Main()
    {
        int count;
        byte[] byteArray;
        char[] charArray;
        UnicodeEncoding uniEncoding = new UnicodeEncoding();

        // Create the data to write to the stream. 
        byte[] firstString = uniEncoding.GetBytes(
            "Invalid file path characters are: ");
        byte[] secondString = uniEncoding.GetBytes(
            Path.GetInvalidPathChars());

        using(MemoryStream memStream = new MemoryStream(100))
        {
            // Write the first string to the stream.
            memStream.Write(firstString, 0 , firstString.Length);

            // Write the second string to the stream, byte by byte.
            count = 0;
            while(count < secondString.Length)
            {
                memStream.WriteByte(secondString[count++]);
            }

            // Write the stream properties to the console.
            Console.WriteLine(
                "Capacity = {0}, Length = {1}, Position = {2}\n",
                memStream.Capacity.ToString(),
                memStream.Length.ToString(),
                memStream.Position.ToString());

            // Set the position to the beginning of the stream.
            memStream.Seek(0, SeekOrigin.Begin);

            // Read the first 20 bytes from the stream.
            byteArray = new byte[memStream.Length];
            count = memStream.Read(byteArray, 0, 20);

            // Read the remaining bytes, byte by byte. 
            while(count < memStream.Length)
            {
                byteArray[count++] =
                    Convert.ToByte(memStream.ReadByte());
            }

            // Decode the byte array into a char array 
            // and write it to the console.
            charArray = new char[uniEncoding.GetCharCount(
                byteArray, 0, count)];
            uniEncoding.GetDecoder().GetChars(
                byteArray, 0, count, charArray, 0);
            Console.WriteLine(charArray);
        }
    }
}
using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
   int count;
   array<Byte>^byteArray;
   array<Char>^charArray;
   UnicodeEncoding^ uniEncoding = gcnew UnicodeEncoding;

   // Create the data to write to the stream. 
   array<Byte>^firstString = uniEncoding->GetBytes( "Invalid file path characters are: " );
   array<Byte>^secondString = uniEncoding->GetBytes( Path::InvalidPathChars );

   MemoryStream^ memStream = gcnew MemoryStream( 100 );
   try
   {
      // Write the first string to the stream.
      memStream->Write( firstString, 0, firstString->Length );

      // Write the second string to the stream, byte by byte.
      count = 0;
      while ( count < secondString->Length )
      {
         memStream->WriteByte( secondString[ count++ ] );
      }


      // Write the stream properties to the console.
      Console::WriteLine( "Capacity = {0}, Length = {1}, " 
      "Position = {2}\n", memStream->Capacity.ToString(), memStream->Length.ToString(), memStream->Position.ToString() );

      // Set the stream position to the beginning of the stream.
      memStream->Seek( 0, SeekOrigin::Begin );

      // Read the first 20 bytes from the stream.
      byteArray = gcnew array<Byte>(memStream->Length);
      count = memStream->Read( byteArray, 0, 20 );

      // Read the remaining bytes, byte by byte. 
      while ( count < memStream->Length )
      {
         byteArray[ count++ ] = Convert::ToByte( memStream->ReadByte() );
      }

      // Decode the Byte array into a Char array  
      // and write it to the console.
      charArray = gcnew array<Char>(uniEncoding->GetCharCount( byteArray, 0, count ));
      uniEncoding->GetDecoder()->GetChars( byteArray, 0, count, charArray, 0 );
      Console::WriteLine( charArray );
   }
   finally
   {
      memStream->Close();
   }
}
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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.