strtolower() for unicode/multibyte strings

Question

I have some text in a non-English/foreign language in my page, but when I try to make it lowercase, it characters are converted into black diamonds containing question marks.

$a = "Երկիր Ավելացնել";
echo $b = strtolower($a);
//returns  ����� ���������

I've set my charset in a metatag, but this didn't fix it.

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

What can I do to convert my string to lowercase without corrupting it?

Solution 1

have your tried using mb_strtolower()?

Solution 2

PHP5 is not UTF-8 compatible, so you still need to resort to the mb extension. I suggest you set the internal encoding of mb to utf-8 and then you can freely use its functions without specifying the charset all the time:

mb_internal_encoding('UTF-8');

...

$b = mb_strtolower($a);
echo $b;

Solution 3

i have found this solution from here

$string = 'Թ';
echo 'Uppercase: '.mb_convert_case($string, MB_CASE_UPPER, "UTF-8").'';
echo 'Lowercase: '.mb_convert_case($string, MB_CASE_LOWER, "UTF-8").'';
echo 'Original: '.$string.'';

works for me (lower case)

Solution 4

Have you tried

http://www.php.net/manual/en/function.mb-strtolower.php

mb_strtolower() and specifying the encoding as the second parameter?

The examples on that page appear to work.

You could also try:

$str = mb_strtolower($str, mb_detect_encoding($str));

Solution 5

Php by default does not know about utf-8. It assumes any string is ASCII, so it strtolower converts bytes containing codes of uppercase letters A-Z to codes of lowercase a-z. As the UTF-8 non-ascii letters are written with two or more bytes, the strtolower converts each byte separately, and if the byte happens to contain code equal to letters A-Z, it is converted. In the result the sequence is broken, and it no longer represents correct character.

To change this you need to configure the mbstring extension:

http://www.php.net/manual/en/book.mbstring.php

to replace strtolower with mb_strtolower or use mb_strtolower direclty. I any case, you need to spend some time to configure the mbstring settings to match your requirements.

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Comments

[Pekka]

@Syom did you specify UTF-8 as the encoding?

[Nick Bastin]

strtolower does actually work on multibyte characters, it just works off of the current locale, which is not usually what you want in these cases.

[SteelBytes]

might also need mb_internal_encoding() first

[Admin]

var_dump(mb_strtolower('ԱԱԱ', mb_detect_encoding('ԱԱԱ'))); // string(6) "աաա" 100% Working!!!!

[Dumitru]

I had the same problem and it's worked for me! Thank you a lot!

[ESP32]

I lost 8 hours with debugging... finaly found that strtolower was the problem.