Re: Converting a C structure to Perl

You are making a common c-programmer mistake, one that I regularly made when I started programming in perl. From what I see of your note you equate scalars with strings. This is not the case. Consider the following:

my $a;
$a = "Mary had a little lamb"; # $a contains a string
$a = 2001;                     # $a now contains a number
$a = '2001';                   # $a STILL contains a number
$a .= 'AD';                    # $a is a string once more :)
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How this prints is another matter. print, printf etc all output strings. This is their nature, they know naught else ;). The simplest way to output the byte value of a number is to use the following:

print pack("i", $a);

This will work the same way whiether you represent your data as a number or as a strng of numeric characters; perl interprets both as a number.

print pack("i", 3000);
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print pack("i", '3000');
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print pack("i", "3000");
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Perhaps something like the simple object below will help you

my $data = Data->new("aa", 65, 1.2, "misc", "data string");
print $data->print_secs();

package Data;

sub new {
    my ($class, $id, $secs, $vers, $misc, $data) = @_;

    my $self = {
        'id' => $id,
        'secs' => $secs,
        'version' => $vers,
        'misc' => $misc,
        'data' => $data,
    };

    bless $self, $class;

    return $self;
}

sub print_secs { # Returns $self->{'secs'} as a byte stream
    $self = shift;

    return pack('i', $self->{'secs'});
}
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This is a bit crude but perhaps it will give you some ideas.

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Re: Re: Converting a C structure to Perl by Fastolfe (Vicar) on Jan 05, 2001 at 19:29 UTC
I don't tend to use it, but I figure mentioning Class::Struct might be interesting to you guys: `use Class::Struct; struct data => { id => '$', secs => '$', version => '$', misc => '$', data => '$', next => 'data', # just an example }; $one = new data (id => 1, secs => 2); $two = new data (id => 2, secs => 2, data => 'hi'); $one->next($two); print $one->next->data; # "hi"` [download]	[reply] [d/l]

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Re: Re: Converting a C structure to Perl
by Fastolfe (Vicar) on Jan 05, 2001 at 19:29 UTC

Class::Struct

use Class::Struct;

struct data => {
   id      => '$',
   secs    => '$',
   version => '$',
   misc    => '$',
   data    => '$',
   next    => 'data',    # just an example
};

$one = new data (id => 1, secs => 2);
$two = new data (id => 2, secs => 2, data => 'hi');
$one->next($two);

print $one->next->data;    # "hi"
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