Bug in BinaryWriter

  • Thread starter Thread starter Zachary Turner
  • Start date Start date
Z

Zachary Turner

I searched Usenet and found some posts with people having similar
problems, I'm wondering if any MVPs or anyone else knows if this is a
confirmed bug and if MS plans to do anything about it. First let me
quite the MSDN documentation:

public virtual void Write ( string value )

A length-prefixed string represents the string length by prefixing to
the string a single byte or word that contains the length of that
string. This method writes a length-prefixed string to this stream
using the BinaryWriter instance's current Encoding. -----This method
first writes the length of the string as a four-byte unsigned
integer-----, and then writes that many characters to the stream.

the section enclosed in ----- ----- indicates where the "bug" arises.
There's either a bug in the documentation or the function, one or the
other.

The following sample program should demonstrate:

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace WriterTest
{
class Program
{
static void Main(string[] args)
{
using (MemoryStream MStream = new MemoryStream())
{
BinaryWriter Writer = new BinaryWriter(MStream);

string TestString = "This is a test string";
System.Console.WriteLine("The writer is at position {0}.",
Writer.BaseStream.Position);

Writer.Write(TestString);

System.Console.WriteLine("Position after
BinaryWriter.Write(String) - {0}, String length - {1}, # of bytes
for size - {2}.", Writer.BaseStream.Position, TestString.Length,
Writer.BaseStream.Position - (long)TestString.Length);
System.Console.ReadLine();
}
}
}
}

Here's the output.

The writer is at position 0.
Position after BinaryWriter.Write(String) - 22, String length - 21,
# of bytes for size - 1.
 
I would say the doc. From my tests it looks like the prefix is using the
hihg bit to indicate if the length keeps using the following bytes or
something similar...
 
Zachary Turner said:
I searched Usenet and found some posts with people having similar
problems, I'm wondering if any MVPs or anyone else knows if this is a
confirmed bug and if MS plans to do anything about it. First let me
quite the MSDN documentation:

public virtual void Write ( string value )

A length-prefixed string represents the string length by prefixing to
the string a single byte or word that contains the length of that
string. This method writes a length-prefixed string to this stream
using the BinaryWriter instance's current Encoding. -----This method
first writes the length of the string as a four-byte unsigned
integer-----, and then writes that many characters to the stream.

the section enclosed in ----- ----- indicates where the "bug" arises.
There's either a bug in the documentation or the function, one or the
other.
Click to expand...

It's a bug in the docs. It's writes a "7 bit encoded" integer as per
the Write7BitEncodedInt method.
 
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