WOW!!! Amazing explanation !! Thank you very very much Ovid =)
But is there anyway to do the "re-converting" without using any module ?
my homework requirement is allow me to do so... ( and I don't know how to
use module yet too). Please give me a hand for a little bit more help, thank
you
very much. ^__^
----- Original Message -----
From: "Curtis Poe" <[EMAIL PROTECTED]>
To: "Connie Chan" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Thursday, December 20, 2001 12:17 PM
Subject: Re: re-convert
> --- Connie Chan <[EMAIL PROTECTED]> wrote:
> > Since we know this : $string =~ s/([a-fA-F0-9][a-fA-F0-9])/pack ("C",
hex($1))/eg;
> >
> > is a statement which can converting back the "real string" from
> > a form field, but, could anybody tell how to convert the "real string"
> > to the "long long" string ??
> >
> > Besides, anybody can tell what is the exactly meaning of : ("C",
hex($1)) ?
>
> Connie,
>
> Here's the scoop:
>
> pack ("C", hex($1))
>
> Working from the inside, out, 'hex' is a function that takes hex input and
returns the integer
> value:
>
> $ perl -e 'print hex "f"'
> 15
>
> The $1 has the hex data captured from the regular expression. From
'perldoc -f pack', we see that
> if the first argument to pack is an upper case C, it will convert the
second argument to an
> unsigned character (ASCII).
>
> $ perl -e '@a=qw/4f 76 69 64/;print pack("C",hex$_)for @a'
> Ovid
>
> To get from an ASCII character back to the hex encoded version, use
URI::Escape.
>
> C:\WINDOWS>perl -MURI::Escape -e "print uri_escape(q|Ovid|)"
> Ovid
>
> You might wonder why that printed "Ovid" instead of a bunch of funky hex
characters. In URIs,
> only certain characters need to be escaped. Ampersands, semi-colons,
spaces, and a few other
> items need escaping. See 'perldoc URI::Escape' for more information.
>
> C:\WINDOWS>perl -MURI::Escape -e "print uri_escape(q|& ;+|)"
> %26%20%3B%2B
>
> For a full list of what characters are escaped in URIs, see
> http://www.easystreet.com/~ovid/cgi_course/appendices/appendix2.html.
There's also a Perl program
> at the bottom of the page which shows the use of the URI::Escape module in
much greater detail.
>
> Cheers,
> Curtis "Ovid" Poe
>
> =====
> "Ovid" on http://www.perlmonks.org/
> Someone asked me how to count to 10 in Perl:
> push@A,$_ for reverse q.e...q.n.;for(@A){$_=unpack(q|c|,$_);@a=split//;
> shift@a;shift@a if $a[$[]eq$[;$_=join q||,@a};print $_,$/for reverse @A
>
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