mb_strtolower

(PHP 4 >= 4.3.0, PHP 5)

mb_strtolower — Make a string lowercase

Description

string mb_strtolower ( string $str [, string $encoding = mb_internal_encoding() ] )

Returns str with all alphabetic characters converted to lowercase.

Parameters

str: The string being lowercased.
encoding: The encoding parameter is the character encoding. If it is omitted, the internal character encoding value will be used.

Return Values

str with all alphabetic characters converted to lowercase.

Unicode

For more information about the Unicode properties, please see » http://www.unicode.org/unicode/reports/tr21/.

By contrast to strtolower(), 'alphabetic' is determined by the Unicode character properties. Thus the behaviour of this function is not affected by locale settings and it can convert any characters that have 'alphabetic' property, such as A-umlaut (Ä).

Examples

Example #1 mb_strtolower() example


<?php
$str = "Mary Had A Little Lamb and She LOVED It So";
$str = mb_strtolower($str);
echo $str; // Prints mary had a little lamb and she loved it so
?>


Note that mb_strtolower() is very SLOW, if you have a database connection, you may want to use it to convert your strings to lower case. Even latin1/9 (iso-8859-1/15) and other encodings are possible.



Have a look at my simple benchmark:



<?php



$text = "Lörem ipßüm dölör ßit ämet, cönßectetüer ädipißcing elit. Sed ligülä. Präeßent jüßtö tellüß, grävidä eü, tempüß ä, mättiß nön, örci. Näm qüiß lörem. Näm äliqüet elit ßed elit. Phäßellüß venenätiß jüßtö eget enim. Dönec nißl. Pröin mättiß venenätiß jüßtö. Sed äliqüäm pörtä örci. Cräß elit nißl, cönvälliß qüiß, tincidünt ät, vehicülä äccümßän, ödiö. Sed möleßtie. Etiäm mölliß feügiät elit. Veßtibülüm änte ipßüm primiß in fäücibüß örci lüctüß et ültriceß pößüere cübiliä Cüräe; Mäecenäß nön nüllä.";



// mb_strtolower()

$timeMB = microtime(true);     

              

    for($i=0;$i<30000;$i++) 

        $lower = mb_strtolower("$text/no-cache-$i");



$timeMB = microtime(true) - $timeMB;



// MySQL lower()

$timeSQL = microtime(true);    



    mysql_query("set names latin1");               

    for($i=0;$i<30000;$i++) { 

        $r = mysql_fetch_row(mysql_query("select lower('$text/no-cache-$i')"));

        $lower = $r[0];

    }



$timeSQL = microtime(true) - $timeSQL;



echo "mb: ".sprintf("%.5f",$timeMB)." sek.<br />";

echo "sql: ".sprintf("%.5f",$timeSQL)." sek.<br />";



// Result on my notebook:

// mb: 11.50642 sek.

// sql: 5.44143 sek.



?>

btherl at yahoo dot com dot au
16-Nov-2005 05:12


If you use this function on a unicode string without telling PHP that it is unicode, then you will corrupt your string.  In particular, the uppercase 'A' with tilde, common in 2-byte UTF-8 characters, is converted to lowercase 'a' with tilde.



This can be handled correctly by:

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



Or if you know your data is UTF-8, just use the string "UTF-8" as the second argument.



You should check also that mb_detect_encoding() is checking the encodings you want it to check, and is detecting the correct encodings.

add a note

mb_strtoupper

mb_strstr

Last updated: Fri, 12 Mar 2010