in reply to Re^3: How do I read a 24 bit integer?
in thread How do I read a 24 bit integer?

Finally understanding this a bit, but it seems like I have one more problem.

First, my code: 

read FILE, $myinput, 12;
my($var1, $var2, $var3, $var4) = unpack('A3A3A3A3', $myinput);
$var1 = unpack ('N', "\x00" . $var1);
$var2 = unpack ('N', "\x00" . $var2);
$var3 = unpack ('N', "\x00" . $var3);
$var4 = unpack ('N', "\x00" . $var4);
print "$var1\n";
print "$var2\n";
print "$var3\n";
print "$var4\n";

[download]
The problem is that some of these values are legitimately zero, and when I try to print them, I get: 
Use of uninitialized value in concatenation (.) or string at myscript.
+pl line 20.

[download]
What did I miss to allow zeroes?

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Re^5: How do I read a 24 bit integer?
by JavaFan (Canon) on Jan 02, 2010 at 11:28 UTC
    Are you sure you actually read 12 bytes? Because it seems one of your variables wasn't set by the unpack (probably the $var4).
[reply]
      I have absolutely no idea. :( But this code: 
      #!/usr/bin/perl -w
use strict;

my $myinput="\x00\x00\x00\x00\x00\x00\x01\x02\x03\x04\x05\x06";
my($var1, $var2, $var3, $var4) = unpack('A3A3A3A3', $myinput);
$var1 = unpack ('N', "\x00" . $var1);
$var2 = unpack ('N', "\x00" . $var2);
$var3 = unpack ('N', "\x00" . $var3);
$var4 = unpack ('N', "\x00" . $var4);
print "$var1\n";
print "$var2\n";
print "$var3\n";
print "$var4\n";

      [download]
      produces: 
      Use of uninitialized value in concatenation (.) or string at ./test2.p
+l line 10.

Use of uninitialized value in concatenation (.) or string at ./test2.p
+l line 11.

66051
263430

      [download]
      when I would expect to see: 
      0
0
66051
264430

      [download]
[reply]
[d/l]
[select]

        Use a template of '(a3)*' ('a' not 'A'), to fix the problem.

        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.
[reply]
[d/l]

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