Character conversion

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Wise Monks,
I have a question regarding special character conversions. At the moment I convert a url string in the following way:


$url_string =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
[download]

How would I convert the other way around? I need to convert characters such as '&',':',etc to their '%' hex equivalents?
Thanks in advance for any help

Comment on Character conversion Download Code

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Re: Character conversion by Roy Johnson (Monsignor) on Feb 22, 2006 at 17:08 UTC
If you insist on rolling your own, something like this: `$url_string =~ s/([^[:alnum:]])/sprintf '%%%02x', ord($1)/eg; # thanks + for the 02, ikegami` [download] but it's probably better to find a module like URI::Escape. Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re^2: Character conversion by ikegami (Patriarch) on Feb 22, 2006 at 17:43 UTC
That should be `%02x`, not `%x`, or else it will fail for `"\x0"` to `"\xF"`. One reason URI::Escape is better is because it fails safely when provided with unicode characters, while your code fails badly.	[reply] [d/l] [select]
Re^2: Character conversion by Anonymous Monk on Feb 22, 2006 at 17:11 UTC
Thanks, This was exactly what I needed..	[reply]
Re: Character conversion by Fletch (Bishop) on Feb 22, 2006 at 17:07 UTC
Gah, no. `URI::Escape::uri_escape`	[reply]
Re: Character conversion by vladb (Vicar) on Feb 22, 2006 at 17:09 UTC
You can convert the other way using this line of code `$str =~ s/([^A-Za-z0-9])/sprintf("%%%02X", ord($1))/seg;` [download] The reverse of what you do in your first regexp, which also could be simplified just a tiny bit like so `$str =~ s/\%([A-Fa-f0-9]{2})/pack('C', hex($1))/seg;` [download] _____________________ "We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true." - Robert Wilensky, University of California	[reply] [d/l] [select]
Re: Character conversion by CountOrlok (Friar) on Feb 22, 2006 at 17:07 UTC
I think you are looking for the escapeHTML method in the CGI module. -imran	[reply]
Re^2: Character conversion by ikegami (Patriarch) on Feb 22, 2006 at 17:31 UTC
No. URIs and HTML have very different escaping mechanisms.	[reply]