Re^2: Binary conditionals

Ok, I can't do a simple s/// because I actually have to rotate them. It's something with the conditional or the assignment. I tried updating the code in this manner

#!/usr/bin/perl

open my $in,  '<:raw', 'out.dat' or die $!;
open my $out, '>:raw', 'outfile.jpg' or die $!;
local $/ = \1024;
my $byte;
while (read($in, $byte, 1)) {
	if($byte == x00){
		$byte = chr(x17);}
	elsif($byte == x17){
		$byte = chr(x00);}
	elsif($byte == x4E){
		$byte = chr(x42);}
	elsif($byte == x42){
		$byte = chr(x4E);}
	elsif($byte == x24){
		$byte = chr(x90);}
	elsif($byte == x90){
		$byte = chr(x24);}
	print $out $byte;
}
close $in or die $!;
close $out or die $!;

all it prints is many nulls and sporadic digits 1..9. I've even tried this with an if($byte eq chr(x00)) but it doesn't work eighther.

Comment on Re^2: Binary conditionals

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Re^3: Binary conditionals by moritz (Cardinal) on Sep 30, 2008 at 18:40 UTC
Always start your scripts with `use strict; use warnings;` [download] It catches many of your errors. The correct comparison is either `$byte eq "\x00"` or `$byte eq chr(0x00)`. You can still use a substitution if your mapping is constant: `my %table = ( "\x00" => "\x17", "\x17" => "\x00", ... ); my $re = join '\|', map quotemeta, keys %table; # open in and out files... # and then substitute: $str =~ s/($re)/$table{$1}/g` [download]	[reply] [d/l] [select]
Re^4: Binary conditionals by bunnym4n (Novice) on Sep 30, 2008 at 18:53 UTC
That worked perfectly! Thank you!	[reply]
Re^3: Binary conditionals by jwkrahn (Abbot) on Sep 30, 2008 at 19:21 UTC
Since only characters are involved you can use `tr///`: `while (<$in>) { tr/\x00\x17\x4E\x42\x24\x90/\x17\x00\x42\x4E\x90\x24/; print $out $_; }` [download]	[reply] [d/l] [select]