URI::Escape(3)                 User Contributed Perl Documentation                 URI::Escape(3)



NAME
       URI::Escape - Escape and unescape unsafe characters

SYNOPSIS
        use URI::Escape;
        $safe = uri_escape("10% is enough\n");
        $verysafe = uri_escape("foo", "\0-\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).  A URI consists of a restricted set of characters, denoted as
       "uric" in RFC 2396.  The restricted set of characters consists 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 character "%" followed by two hexadecimal digits.  A byte can also be
       represented directly by a character, using the US-ASCII 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 )
       uri_escape( $string, $unsafe )
           Replaces each unsafe character in the $string with the corresponding escape sequence
           and returns the result.  The $string argument should be a string of bytes.  The
           uri_escape() function will croak if given a characters with code above 255.  Use
           uri_escape_utf8() if you know you have such chars or/and want chars in the 128 .. 255
           range treated as UTF-8.

           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.:

             "\x00-\x1f\x7f-\xff"          # all control and hi-bit characters
             "a-z"                         # all lower case characters
             "^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_escape_utf8( $string )
       uri_escape_utf8( $string, $unsafe )
           Works like uri_escape(), but will encode chars as UTF-8 before escaping them.  This
           makes this function able do deal with characters with code above 255 in $string.  Note
           that chars in the 128 .. 255 range will be escaped differently by this function com-
           pared to what uri_escape() would.  For chars in the 0 .. 127 range there is no differ-
           ence.

           The call:

               $uri = uri_escape_utf8($string);

           will be the same as:

               use Encode qw(encode);
               $uri = uri_escape(encode("UTF-8", $string));

           but will even work for perl-5.6 for chars in the 128 .. 255 range.

           Note: Javascript has a function called escape() that produce the sequence "%uXXXX" for
           chars in the 256 .. 65535 range.  This function has really nothing to do with URI
           escaping but some folks got confused since it "does the right thing" in the 0 .. 255
           range.  Because of this you sometimes see "URIs" with these kind of escapes.  The
           JavaScript encodeURI() function is similar to uri_escape_utf8().

       uri_unescape($string,...)
           Returns a string with each %XX sequence 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 did, calling the function (instead of the inline RE
           above) if a few chars were unescaped was something like 40% slower, and something like
           700% slower if none were.  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 returned
           unescaped.

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

SEE ALSO
       URI

COPYRIGHT
       Copyright 1995-2004 Gisle Aas.

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



perl v5.8.8                                 2008-04-02                             URI::Escape(3)