How to get a MemoryStream from a Stream in NET

Question

I have the following constructor method which opens a MemoryStream from a file path   MemoryStream  ms   public MyClass string filePath        byte   docBytes   File ReadAllBytes filePath        ms   new MemoryStream         ms Write docBytes  0  docBytes Length       I need to change this to accept a Stream instead of a file path  Whats the easiest most efficient way to get a MemoryStream from the Stream object

User · Answer

In  NET 4  you can use Stream CopyTo to copy a stream  instead of the home-brew methods listed in the other answers   MemoryStream  ms   public MyClass Stream sourceStream        ms   new MemoryStream        sourceStream CopyTo  ms

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If you re modifying your class to accept a Stream instead of a filename  don t bother converting to a MemoryStream  Let the underlying Stream handle the operations   public class MyClass        Stream  s       public MyClass Stream s     s   s        But if you really need a MemoryStream for internal operations  you ll have to copy the data out of the source Stream into the MemoryStream   public MyClass Stream stream         ms   new MemoryStream        CopyStream stream   ms         Merged From linked CopyStream below and Jon Skeet s ReadFully example public static void CopyStream Stream input  Stream output        byte   buffer   new byte 16 1024       int read      while  read   input Read  buffer  0  buffer Length    gt  0                output Write  buffer  0  read

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byte   fileData   null  using  var binaryReader   new BinaryReader Request Files 0  InputStream         fileData   binaryReader ReadBytes Request Files 0  ContentLength

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You will have to read in all the data from the Stream object into a byte   buffer and then pass that into the MemoryStream via its constructor   It may be better to be more specific about the type of stream object you are using   Stream is very generic and may not implement the Length attribute  which is rather useful when reading in data   Here s some code for you   public MyClass Stream inputStream        byte   inputBuffer   new byte inputStream Length       inputStream Read inputBuffer  0  inputBuffer Length         ms   new MemoryStream inputBuffer       If the Stream object doesn t implement the Length attribute  you will have to implement something like this   public MyClass Stream inputStream        MemoryStream outputStream   new MemoryStream         byte   inputBuffer   new byte 65535       int readAmount      while  readAmount   inputStream Read inputBuffer  0  inputBuffer Length    gt  0          outputStream Write inputBuffer  0  readAmount         ms   outputStream

User · Answer

Use this   var memoryStream   new MemoryStream    stream CopyTo memoryStream     This will convert Stream to MemoryStream

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You can simply do   var ms   new MemoryStream File ReadAllBytes filePath      Stream position is 0 and ready to use

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I use this combination of extension methods       public static Stream Copy this Stream source                if  source    null              return null           long originalPosition   -1           if  source CanSeek              originalPosition   source Position           MemoryStream ms   new MemoryStream             try                       Copy source  ms                if  originalPosition  gt  -1                  ms Seek originalPosition  SeekOrigin Begin               else                 ms Seek 0  SeekOrigin Begin                return ms                    catch                       ms Dispose                throw                       public static void Copy this Stream source  Stream target                if  source    null              throw new ArgumentNullException  source            if  target    null              throw new ArgumentNullException  target             long originalSourcePosition   -1          int count   0          byte   buffer   new byte 0x1000            if  source CanSeek                        originalSourcePosition   source Position              source Seek 0  SeekOrigin Begin                      while   count   source Read buffer  0  buffer Length    gt  0              target Write buffer  0  count            if  originalSourcePosition  gt  -1                        source Seek originalSourcePosition  SeekOrigin Begin

User · Answer

public static void Do Stream in         ms   new MemoryStream        byte   buffer   new byte 65536       while   int read   input Read buffer  0  buffer Length   gt  0           ms Write  buffer  0  read

User · Answer

How do I copy the contents of one stream to another   see that  accept a stream and copy to memory  you should not use  Length for just Stream because it is not necessarily implemented in every concrete Stream

[c#] How to get a MemoryStream from a Stream in .NET?

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