Problem in UTF Encoding in PHP

Question

I use the following lines of code:

$revTerm =  "". strrev($limitAry["term"]);
$revTerm = utf8_encode($revTerm);

The $revTerm contains Norwegian characters as ø æ å. However, it is shown correctly. I need to reverse them before displaying, so I use the first line. When I display them this way, I get an error of bad xml format - used to fill a grid. When I try to use the second line, I don't get an error but the characters are not shown correctly. Could there be any other way to solve that? If it may help, I use jqGrid to fill those data in.

As you use utf8_encode, the string in $limitAry["term"] is encoded with ISO 8859-1, right? — Gumbo
– Gumbo, Commented Feb 7, 2011 at 9:17
The string is already destroyed before he calls utf8_encode. Since strrev is written for single-byte encodings, it swaps the order of bytes that were part of single multi-byte characters, effectively turning them into different characters or nonsensical byte sequences. — Dan Grossman
– Dan Grossman, Commented Feb 7, 2011 at 9:22
@Dan Grossman: I just don’t see the point for utf8_encode. If $limitAry["term"] were ISO 8859-1 (or any other single-byte character encoding), strrev would work and utf8_encode would convert that reversed string to UTF-8 (including incorrect mapping if $limitAry["term"] is not ISO 8859-1). But if $limitAry["term"] already were UTF-8, strrev would not work properly and using utf8_encode wouldn’t make any sense as it’s already UTF-8. But none of these scenarios explain the XML error. — Gumbo
– Gumbo, Commented Feb 7, 2011 at 9:48

Dan Grossman · Accepted Answer · 2011-02-07 09:15:44Z

4

strrev, like most PHP string functions, is not safe for multi-byte encodings.

answered Feb 7, 2011 at 9:15

Dan Grossman

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2 Comments

Ignacio Vazquez-Abrams Over a year ago

To be fair, it can be used for UCS-2 and UCS-4, however it changes the endianness of the string.

Dan Grossman Over a year ago

You'll have to write it yourself, right, and only make use of the functions in PHP's multibyte library (which doesn't include a built-in string reversing function): php.net/manual/en/book.mbstring.php

Vadym · Accepted Answer · 2013-07-24 16:28:17Z

3

try this example

$test = 'А роза упала на лапу Азора ウィキ';
$test = iconv('utf-8', 'utf-16le', $test);
$test = strrev($test);
// キィウ арозА упал ан алапу азор А
echo iconv('utf-16be', 'utf-8', $test);

(russian) http://bolknote.ru/2012/04/02/~3625#56

answered Jul 24, 2013 at 16:28

Vadym

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1 Comment

user1643723 Over a year ago

Short explanation for people, who don't understand Russian: this will correctly reverse order of most multibyte string as long as they consist from single-codepoint symbols. It abuses the fact, that byte-by-byte reversion of UTF-16 produces correctly reversed UTF-16 string, but in different endianess. It won't work for complex graphemes (such as most emojis, certain forms of characters with accents etc). A handy article about the multi-codepoint symbols: developer.apple.com/library/content/documentation/Cocoa/…

Floern · Accepted Answer · 2011-02-07 09:19:56Z

0

Try this:

$revTerm = utf8_decode($limitAry["term"]);
$revTerm = strrev($revTerm);
$revTerm = utf8_encode($revTerm);

For using strrev you have to decode your string to a non-multibyte string.

answered Feb 7, 2011 at 9:19

Floern

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1 Comment

Dan Grossman Over a year ago

That only works if all the characters in the string exist in the ISO-8859-1 character set

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