uri::escape(3)

NAME

URI::Escape - Escape and unescape unsafe characters

SYNOPSIS

use URI::Escape;
$safe = uri_escape("10% is enough0);
$verysafe = uri_escape("foo", " -377");
$str  = uri_unescape($safe);

DESCRIPTION

This module provides functions to escape and unescape URI
strings as defined by RFC 2396 (and updated by RFC 2732).
URIs consist of a restricted set of characters, denoted as
"uric" in RFC 2396. The restricted set of characters con
sists of digits, letters, and a few graphic symbols chosen
from those common to most of the character encodings and
input facilities available to Internet users:

"A" .. "Z", "a" .. "z", "0" .. "9",
";", "/", "?", ":", "@", "&", "=", "+", "$", ",", "[",

"]", # reserved
"-", "_", ".", "!", "~", "*", "'", "(", ")"

In addition any byte (octet) can be represented in a URI
by an escape sequence; a triplet consisting of the charac
ter "%" followed by two hexadecimal digits. Bytes can
also be represented directly by a character using the USASCII character for that octet (iff the character is part
of "uric").

Some of the "uric" characters are reserved for use as
delimiters or as part of certain URI components. These
must be escaped if they are to be treated as ordinary
data. Read RFC 2396 for further details.

The functions provided (and exported by default) from this
module are:

uri_escape($string, [$unsafe])

This function replaces all unsafe characters in the
$string with their escape sequences and returns the
result.

The uri_escape() function takes an optional second argument that overrides the set of characters that are
to be escaped. The set is specified as a string that
can be used in a regular expression character class
(between [ ]). E.g.:

"0-ff-" # all control and hi-bit characters
"a-z" # all lower case char

acters
"^A-Za-z" # everything not a

letter

The default set of characters to be escaped is all
those which are not part of the "uric" character class
shown above as well as the reserved characters. I.e.
the default is:

"^A-Za-z0-9-_.!~*'()"

uri_unescape($string,...)

Returns a string with all %XX sequences replaced with
the actual byte (octet).

This does the same as:

$string =~ s/%([0-9A-Fa-f]{2})/chr(hex($1))/eg;

but does not modify the string in-place as this RE
would. Using the uri_unescape() function instead of the RE might make the code look cleaner and is a few
characters less to type.

In a simple benchmark test I made I got something like
40% slowdown by calling the function (instead of the
inline RE above) if a few chars where unescaped and
something like 700% slowdown if none where. If you
are going to unescape a lot of times it might be a
good idea to inline the RE.

If the uri_unescape() function is passed multiple strings, then each one is unescaped returned.

The module can also export the %escapes hash which con
tains the mapping from all 256 bytes to the corresponding
escape code. Lookup in this hash is faster than evaluat
ing "sprintf("%%%02X", ord($byte))" each time.

SEE ALSO

URI

COPYRIGHT

Copyright 1995-2001 Gisle Aas.

This program is free software; you can redistribute it
and/or modify it under the same terms as Perl itself.

perl v5.8.0 2002-07-19 URI::Escape(3)