trimming string converted from byte[]

[Rico]

In the following piece of code:
************************************************** *****
byte[] buffer = new byte[20];
string next_node=null, ret=null;
ASCIIEncoding encoding = new ASCIIEncoding();
BufferedStream sr = new BufferedStream (new FileStream (nodeptr, FileMode.Open ));

sr.Seek(6, SeekOrigin.Begin );
sr.Read (buffer, 0, 17);
next_node = encoding.GetString(buffer);

Console.WriteLine(next_node.Trim() + "__");
************************************************** *****

I read 17 bytes from a text file as from the 7th byte onwards.
Why is it that the final WriteLine statement shows what appears to be
characters with ASCII code 0 in next_node before the "__" ?

A work-around is to set the size of buffer to exactly the number of bytes
I happen to know I need to read. What when I don't and overallocate space
in buffer, or when Read() says fewer bytes than requested were read and I
only want to convert those to a string?

Rico.

[Jon Skeet [C# MVP]]

Rico <ra*****@yahoo.com> wrote:

In the following piece of code:
************************************************** *****
byte[] buffer = new byte[20];
string next_node=null, ret=null;
ASCIIEncoding encoding = new ASCIIEncoding();
This line is unnecessary - you can just use Encoding.ASCII to avoid
creating a new encoding each time.
BufferedStream sr = new BufferedStream (new FileStream (nodeptr, FileMode.Open ));

sr.Seek(6, SeekOrigin.Begin );
sr.Read (buffer, 0, 17);
next_node = encoding.GetString(buffer);

Console.WriteLine(next_node.Trim() + "__");
************************************************** *****

I read 17 bytes from a text file as from the 7th byte onwards.
Why is it that the final WriteLine statement shows what appears to be
characters with ASCII code 0 in next_node before the "__" ?
Because you've presented it with a buffer of 20 bytes and asked it to
convert the whole of it to a string - it's done exactly what you asked
it to.
A work-around is to set the size of buffer to exactly the number of bytes
I happen to know I need to read. What when I don't and overallocate space
in buffer, or when Read() says fewer bytes than requested were read and I
only want to convert those to a string?

You should use the return value of Read to know how much you've
actually read, and then use
Encoding.ASCII.GetString(buffer, 0, bytesRead);

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Rico]

On Wed, 04 Aug 2004 08:52:16 +0100, Jon Skeet[ C# MVP] wrote:

You should use the return value of Read to know how much you've
actually read, and then use
Encoding.ASCII.GetString(buffer, 0, bytesRead);

I know this group is quite busy but it still seems there's space and
bandwidth for a 'Thank You Jon'.

Rico.