--- 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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