Beefy Boxes and Bandwidth Generously Provided by pair Networks
XP is just a number
 
PerlMonks  

Re: unpack() removing data

by BrowserUk (Pope)
on Jan 10, 2013 at 22:17 UTC ( #1012750=note: print w/ replies, xml ) Need Help??


in reply to unpack() removing data

open FILE, "temp.bin" or die $!; binmode FILE; open OUTFILE2, ">", "outfile2.txt" or die $!; while (<FILE>) {

Reading a binary file using realine (aka. the <> operator) is wrong. Depending on your OS and the current setting of $/, weird things can happen when a binary value (integer; short, long,long; signed, unsigned) happens to contain a byte that looks like the delimiter.

You should use read or sysread or set $/ = undef and slurp, or set $/ = \nnn; and read fixed length chunks.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.


Comment on Re: unpack() removing data
Select or Download Code
Re^2: unpack() removing data
by shnatko (Initiate) on Jan 10, 2013 at 22:55 UTC
    The strange part is that gives me the results I'm expecting ( byte not stripped out ). It's NOT reading the binary results from the temp.bin file which is causing me problems.

      On my system (Fedora 17, perl v5.14.3) it strips out hex 0D (CR) in both cases. Handling of line terminators is documented as being system-dependent, though. Without knowing exactly which character being deleted (and the characters before and after it) and what flavor of system you are running on it's hard to guess what the problem might be. You might try this and see if the two dumps are different; if they are you can start looking at sg_logs rather than at your perl script...

      sg_logs --page=0x34,1 pd1 -H -r > temp.bin od -x temp.bin | head sg_logs --page=0x34,1 pd1 -H -r | od -x | head
        the system is win7 strawberry perl 5.12.3.0. it does look like the byte being removed is 0x0d consistently. i'll explore that a bit. this is a good lead. thanks!

      Without sample data (ie. the output from sglogs which I have no knowledge of), I cannot guess further.

      But I bet the root cause is the reading or writing of binary values using functions designed for delimited text.


      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1012750]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others having an uproarious good time at the Monastery: (9)
As of 2014-07-22 23:56 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    My favorite superfluous repetitious redundant duplicative phrase is:









    Results (130 votes), past polls