Writing String to Stream and reading it back does not work

Question

I want to write a String to a Stream  a MemoryStream in this case  and read the bytes one by one    stringAsStream   new MemoryStream    UnicodeEncoding uniEncoding   new UnicodeEncoding    String message    Message    stringAsStream Write uniEncoding GetBytes message   0  message Length    Console WriteLine  This  t t     char uniEncoding GetBytes message  0    Console WriteLine  Differs from  t     char stringAsStream ReadByte       The  undesired  result I get is   This          M Differs from      It looks like it s not being read correctly  as the first char of  Message  is  M   which works when getting the bytes from the UnicodeEncoding instance but not when reading them back from the stream   What am I doing wrong     The bigger picture  I have an algorithm which will work on the bytes of a Stream  I d like to be as general as possible and work with any Stream  I d like to convert an ASCII-String into a MemoryStream  or maybe use another method to be able to work on the String as a Stream  The algorithm in question will work on the bytes of the Stream

User · Answer

You need to reset the stream to the beginning:

stringAsStream.Seek(0, SeekOrigin.Begin);
Console.WriteLine("Differs from:\t" + (char)stringAsStream.ReadByte());

This can also be done by setting the Position property to 0:

stringAsStream.Position = 0

User · Answer

After you write to the MemoryStream and before you read it back  you need to Seek back to the beginning of the MemoryStream so you re not reading from the end   UPDATE  After seeing your update  I think there s a more reliable way to build the stream   UnicodeEncoding uniEncoding   new UnicodeEncoding    String message    Message       You might not want to use the outer using statement that I have    I wasn t sure how long you would need the MemoryStream object     using MemoryStream ms   new MemoryStream          var sw   new StreamWriter ms  uniEncoding       try               sw Write message           sw Flush     otherwise you are risking empty stream         ms Seek 0  SeekOrigin Begin               Test and work with the stream here              If you need to start back at the beginning  be sure to Seek again            finally               sw Dispose              As you can see  this code uses a StreamWriter to write the entire string  with proper encoding  out to the MemoryStream  This takes the hassle out of ensuring the entire byte array for the string is written   Update  I stepped into issue with empty stream several time  It s enough to call Flush right after you ve finished writing

User · Answer

Try this  one-liner  from Delta s Blog  String To MemoryStream  C     MemoryStream stringInMemoryStream      new MemoryStream ASCIIEncoding Default GetBytes  Your string here       The string will be loaded into the MemoryStream  and you can read from it  See Encoding GetBytes       which has also been implemented for a few other encodings

User · Answer

I think it would be a lot more productive to use a TextWriter  in this case a StreamWriter to write to the MemoryStream  After that  as other have said  you need to  rewind  the MemoryStream using something like stringAsStream Position   0L    stringAsStream   new MemoryStream        create stream writer with UTF-16  Unicode  encoding to write to the memory stream using StreamWriter sWriter   new StreamWriter stringAsStream  UnicodeEncoding Unicode       sWriter Write  Lorem ipsum       stringAsStream Position   0L     rewind   Note that      StreamWriter defaults to using an instance of UTF8Encoding  unless specified otherwise  This instance of UTF8Encoding  is constructed without a byte order mark  BOM    Also  you don t have to create a new UnicodeEncoding   usually  since there s already one as a static member of the class for you to use in convenient utf-8  utf-16  and utf-32 flavors   And then  finally  as others have said  you re trying to convert the bytes directly to chars  which they are not  If I had a memory stream and knew it was a string  I d use a TextReader to get the string back from the bytes  It seems  dangerous  to me to mess around with the raw bytes

User · Answer

You re using message Length which returns the number of characters in the string  but you should be using the nubmer of bytes to read  You should use something like   byte   messageBytes   uniEncoding GetBytes message   stringAsStream Write messageBytes  0  messageBytes Length     You re then reading a single byte and expecting to get a character from it just by casting to char  UnicodeEncoding will use two bytes per character   As Justin says you re also not seeking back to the beginning of the stream   Basically I m afraid pretty much everything is wrong here  Please give us the bigger picture and we can help you work out what you should really be doing  Using a StreamWriter to write and then a StreamReader to read is quite possibly what you want  but we can t really tell from just the brief bit of code you ve shown

[c#] Writing String to Stream and reading it back does not work

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