Push Buffered string into array

[Geek8]

How would I push a buffered string of 5 char's into an array that would break them into individual pieces? What I am trying to do is open a file, access the first of 5000 records which are each 5 bytes long and separated by a linefeed. Check to ensure values 2 and 4 are equal and 1 and 3 are not. Then output a count to an output file and then grab the next record and process the same till I get to the end of all records. This is what I have so far, but any help or ideas would be much appreciated. I have just begun using Perl, and am still getting into it and am not aware of all its components.

#!/usr/bin/perl -w
use strict;

undef $/;

open(INPUTFILE, "/u01/home/test_perl.dat"
or die "Couldn't open /u01/home/test_perl.dat for reading: $!\n";
open(OUTPUTFILE, ">//u01/home/countfile.dat"
while (read INPUTFILE, $buffer, 5) {
$string = $buffer; <-----THIS IS WHERE I AM CONFUSED
@array = split(//,$string);

foreach (@array){


Thanks in advance for you help.

Geek8

 

[fishiface]

If your linefeed character is &quot;\n&quot; then you can read the file line by line. If it is &quot;\r&quot;, then you can set the input record separator ($/) to &quot;\r&quot; and then just use normal line-by-line reading semantics such as

    while(<INPUTFILE>) {

More details in the perlvar man page.

Either way, you will then have your five-byte atoms available in $_ at which point [tt]unpack[/tt] is your friend:

    ($a,$b,$c,$d,$e) = unpack('C5',$_);

will assign your five bytes to $a through $e. You could also just:

    my @byte = unpack('C5',$_);

and then use

$byte[0]

,

$byte[1]

, etc.

More details of unpack in the perlfunc manpage.

The completed fragment (?) would then be:

    #!/usr/bin/perl -w
    use strict;

    my $ifile = '/u01/home/test_perl.dat';
    open(INPUTFILE, $ifile) # note no semicolon here!
         or die "$0: Couldn't open $ifile: $!";
    my $ofile = '/u01/home/countfile.dat';
    open(OUTPUTFILE, ">$ofile")
         or die "$0: Couldn't open $ofile: $!";

    while (<INPUTFILE>) {
        my @byte = unpack('C5',$_);
        die &quot;2 != 4&quot; unless $byte[1] == $byte[3];
        die &quot;1 == 3&quot; unless $byte[0] != $byte[2];
        # don't understand what you want with the countfile
    }

I hope that this helps,

Yours,


fish

&quot;As soon as we started programming, we found to our surprise that it wasn't as easy to get programs right as we had thought. Debugging had to be discovered. I can remember the exact instant when I realized that a large part of my life from then on was going to be spent in finding mistakes in my own programs.&quot;
--Maurice Wilkes

 

[Geek8]

Thanks Fish. I will try it out. It makes much more sense. The countfile is for keeping a running count of the records and how many times certain records happen. Ex. How many times a certain indicator is on while another is off, then how many times both are off..etc. Is there a better way to do this thank what you have shown above? If not, thanks for your help and I will try it out anyway.

 

[Geek8]

According to the response Fish gave me above, would this have a problem for a record that is 2733 bytes in lenght and using Unpack I try to place it into a array. For example:

my @byte = unpack('C2733',$_);

the when trying to reference $byte[3], I get the following error.

&quot;Use of uninitialized value in concatenation (.) or string&quot;

Can someone tell me why? The only change I have made to the code Fish provided is changing C5 to C2733.

Thanks

Geek