do you have any idea for this strange behaviour ?

Frankly, no. When I run the version I posted on my system: 

C:\test>del ch

C:\test>type junk4.pl
#!/usr/bin/perl
use strict;

srand();

my $fil = "ch";
open( OUT, '>>', $fil ) or die $!;
binmode OUT;

for my $i ( 1  .. 10_000 ) {
    my $j = int( rand( 20_000 ) ) + 440_000;
    my $k = substr( pack( 'l>', $j ), 1 );
    print OUT $k;
}

close( OUT );
print "DONE !";

C:\test>junk4
DONE !
C:\test>dir ch
 Volume in drive C has no label.
 Volume Serial Number is 8C78-4B42

 Directory of C:\test

13/10/2011  15:29            30,000 ch
               1 File(s)         30,000 bytes
               0 Dir(s)  119,252,598,784 bytes free

[download]

I get exactly the result you'd expect?

Are you running it via a webserver? If so, maybe that has something to do with it, but that's not my arena.

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.

In reply to Re^6: 3-byte representation by BrowserUk
in thread 3-byte representation by gerleu

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