Memory​Stream Class

Definition

Creates a stream whose backing store is memory.

[System.Runtime.InteropServices.ComVisible(true)]
public class MemoryStream : System.IO.Stream
Inheritance
Attributes

Inherited Members

System.IO.Stream

System.MarshalByRefObject

System.Object

Examples

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

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();
   }
}
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);
        }
    }
}
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

Remarks

Note

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.

Note

This type implements the IDisposable interface, but does not actually have any resources to dispose. This means that disposing it by directly calling Dispose() or by using a language construct such as using (in C#) or Using (in Visual Basic) is not necessary.

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.

Constructors

Memory​Stream()

Initializes a new instance of the MemoryStream class with an expandable capacity initialized to zero.

Memory​Stream(​Byte[])

Initializes a new non-resizable instance of the MemoryStream class based on the specified byte array.

Memory​Stream(​Int32)

Initializes a new instance of the MemoryStream class with an expandable capacity initialized as specified.

Memory​Stream(​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.

Memory​Stream(​Byte[], ​Int32, ​Int32)

Initializes a new non-resizable instance of the MemoryStream class based on the specified region (index) of a byte array.

Memory​Stream(​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.

Memory​Stream(​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.

Properties

Can​Read

Gets a value indicating whether the current stream supports reading.

Can​Seek

Gets a value indicating whether the current stream supports seeking.

Can​Write

Gets a value indicating whether the current stream supports writing.

Capacity

Gets or sets the number of bytes allocated for this stream.

Length

Gets the length of the stream in bytes.

Position

Gets or sets the current position within the stream.

Methods

Begin​Read(​Byte[], ​Int32, ​Int32, ​Async​Callback, ​Object)
Begin​Write(​Byte[], ​Int32, ​Int32, ​Async​Callback, ​Object)
Copy​To(​Stream, ​Int32)
Copy​To​Async(​Stream, ​Int32, ​Cancellation​Token)

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

Dispose(​Boolean)

Releases the unmanaged resources used by the MemoryStream class and optionally releases the managed resources.

End​Read(​IAsync​Result)
End​Write(​IAsync​Result)
Flush()

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

Flush​Async(​Cancellation​Token)

Asynchronously clears all buffers for this stream, and monitors cancellation requests.

Get​Buffer()

Returns the array of unsigned bytes from which this stream was created.

Read(​Byte[], ​Int32, ​Int32)

Reads a block of bytes from the current stream and writes the data to a buffer.

Read​Async(​Byte[], ​Int32, ​Int32, ​Cancellation​Token)

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.

Read​Byte()

Reads a byte from the current stream.

Seek(​Int64, ​Seek​Origin)

Sets the position within the current stream to the specified value.

Set​Length(​Int64)

Sets the length of the current stream to the specified value.

To​Array()

Writes the stream contents to a byte array, regardless of the Position property.

Try​Get​Buffer(​Array​Segment<​Byte>)

Returns the array of unsigned bytes from which this stream was created. The return value indicates whether the conversion succeeded.

Write(​Byte[], ​Int32, ​Int32)

Writes a block of bytes to the current stream using data read from a buffer.

Write​Async(​Byte[], ​Int32, ​Int32, ​Cancellation​Token)

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.

Write​Byte(​Byte)

Writes a byte to the current stream at the current position.

Write​To(​Stream)

Writes the entire contents of this memory stream to another stream.