RE: (3) Hex Embedded Images (missing something obvious?)

Yeah, I did copy it yesterday, but I still get this error:

Too many arguments for substr at ./gif2hex.perl line 17, near "'')"
Execution of ./gif2hex.perl aborted due to compilation errors.
[download]

with today's code from your home node:

#!/usr/bin/perl -w

# Description: Hex embedded images sample
# Date:        June 28, 2000
# Author:      bbq@zaz.com.br
# URL:         http://johnny.warp.psi.br/perl/images.pl?img=text

open IMG, "./arrow.gif"
       or die "Couldn't open image: $!\n";

binmode(IMG);
undef $/;
$image = <IMG>;
$hex = unpack("H*", $image);
close IMG;

while ($txt = substr($hex,0,32,'')) {
       print "'$txt'\n";
       }

# END
[download]

Thanks for you help - hope I'm not missing something obvious.
This is definately CUFP.
ybiC

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RE: RE: RE: RE: Hex Embedded Images by btrott (Parson) on Jun 28, 2000 at 22:24 UTC
You're getting this compilation error because you have an older version of Perl. I'm guessing Perl 5.004 or something? Or less, perhaps. That version of substr wasn't added until 5.005. In the docs: `An alternative to using substr() as an lvalue is to specify the replacement string as the 4th argument. This allows you to replace parts of the EXPR and return what was there before in one operation, just as you can with splice().` [download] You'll probably have to make do w/ a two-step operation; first get the first 32 characters using substr, then strip the first 32 characters: `while ($txt = substr($hex, 0, 32)) { substr($hex, 0, 32) = ""; print "'$txt'\n"; }` [download] See if that works for you.	[reply] [d/l] [select]

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RE: RE: RE: RE: Hex Embedded Images
by btrott (Parson) on Jun 28, 2000 at 22:24 UTC

That version of substr wasn't added until 5.005. In the docs:

    An alternative to using substr() as an lvalue is to
    specify the replacement string as the 4th argument.
    This allows you to replace parts of the EXPR and
    return what was there before in one operation,
    just as you can with splice().
[download]

substr

    while ($txt = substr($hex, 0, 32)) {
        substr($hex, 0, 32) = "";
        print "'$txt'\n";
    }
[download]

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