strtolower

(PHP 4, PHP 5, PHP 7, PHP 8)

strtolowerMake a string lowercase

Description

strtolower(string $string): string

Returns string with all ASCII alphabetic characters converted to lowercase.

Bytes in the range "A" (0x41) to "Z" (0x5a) will be converted to the corresponding lowercase letter by adding 32 to each byte value.

This can be used to convert ASCII characters within strings encoded with UTF-8, since multibyte UTF-8 characters will be ignored. To convert multibyte non-ASCII characters, use mb_strtolower().

Parameters

string

The input string.

Return Values

Returns the lowercased string.

Changelog

Version Description
8.2.0 Case conversion no longer depends on the locale set with setlocale(). Only ASCII characters will be converted.

Examples

Example #1 strtolower() example

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

Notes

Note: This function is binary-safe.

See Also

add a note

User Contributed Notes 13 notes

up
113
marcin at maydesign dot pl
14 years ago
strtolower(); doesn't work for polish chars

<?php strtolower("mĄkA"); ?>
will return: mĄka;

the best solution - use mb_strtolower()

<?php mb_strtolower("mĄkA",'UTF-8'); ?>
will return: mąka
up
36
coder at bulgaria dot bg
15 years ago
for cyrillic and UTF 8 use mb_convert_case

exampel

<?php
$string
= "Австралия";
$string = mb_convert_case($string, MB_CASE_LOWER, "UTF-8");
echo
$string;

//output is: австралия
?>
up
25
helvete at bahno dot net
9 years ago
It is worth noting that
<?php
var_dump
(strtolower(null))
?>
returns:
string(0) ""
up
10
dbers26 at gmail dot com
15 years ago
the function arraytolower will create duplicate entries since keys are case sensitive.

<?php
$array
= array('test1' => 'asgAFasDAAd', 'TEST2' => 'ASddhshsDGb', 'TeSt3 '=> 'asdasda@asdadadASDASDgh');

$array = arraytolower($array);
?>
/*
Array
(
[test1] => asgafasdaad
[TEST2] => ASddhshsDGb
[TeSt3] => asdasda@asdadadASDASDgh
[test2] => asddhshsdgb
[test3] => asdasda@asdadadasdasdgh
)
*/

I prefer this method

<?php
function arraytolower($array, $include_leys=false) {

if(
$include_leys) {
foreach(
$array as $key => $value) {
if(
is_array($value))
$array2[strtolower($key)] = arraytolower($value, $include_leys);
else
$array2[strtolower($key)] = strtolower($value);
}
$array = $array2;
}
else {
foreach(
$array as $key => $value) {
if(
is_array($value))
$array[$key] = arraytolower($value, $include_leys);
else
$array[$key] = strtolower($value);
}
}

return
$array;
}
?>

which when used like this

<?php
$array
= $array = array('test1' => 'asgAFasDAAd', 'TEST2' => 'ASddhshsDGb', 'TeSt3 '=> 'asdasda@asdadadASDASDgh');

$array1 = arraytolower($array);
$array2 = arraytolower($array,true);

print_r($array1);
print_r($array2);
?>

will give output of

Array
(
[test1] => asgafasdaad
[TEST2] => asddhshsdgb
[TeSt3] => asdasda@asdadadasdasdgh
)
Array
(
[test1] => asgafasdaad
[test2] => asddhshsdgb
[test3] => asdasda@asdadadasdasdgh
)
up
5
patricia at steuerungb dot de
17 years ago
When you're not sure, how the current locale is set, you might find the following function useful. It's strtolower for utf8-formatted text:

<?php
function strtolower_utf8($inputString) {
$outputString = utf8_decode($inputString);
$outputString = strtolower($outputString);
$outputString = utf8_encode($outputString);
return
$outputString;
}
?>

It's not suitable for every occasion, but it surely gets in handy. I use it for lowering German 'Umlauts' like ä and ö.
up
2
mhuggins57 at yahoo dot com
19 years ago
There's a ucfirst "function" to make the first character uppercase, but there's no "lcfirst" function to make the first character lowercase. Here's my own code to accomplish this.

<?
function lcfirst($str) {
return strtolower(substr($str, 0, 1)) . substr($str, 1);
}
?>

I found this particularly useful for generating XML nodes with the Reflection class.
up
3
rodrigoATsistemasparainternetDOTcomDOTbr
16 years ago
<?php
function fullLower($str){
// convert to entities
$subject = htmlentities($str,ENT_QUOTES);
$pattern = '/&([a-z])(uml|acute|circ';
$pattern.= '|tilde|ring|elig|grave|slash|horn|cedil|th);/e';
$replace = "'&'.strtolower('\\1').'\\2'.';'";
$result = preg_replace($pattern, $replace, $subject);
// convert from entities back to characters
$htmltable = get_html_translation_table(HTML_ENTITIES);
foreach(
$htmltable as $key => $value) {
$result = ereg_replace(addslashes($value),$key,$result);
}
return(
strtolower($result));
}

echo
fullLower("Ã É Ò Õ ÚÙÛ");

//results ã é ò õ úùû
//adapted from fullUpper on strtoupper manual
?>
up
0
rok dot kralj at gmail dot com
17 years ago
Slovenian characters

<?php
function strtolower_slovenian($string)
{
$low=array("Č" => "č", "Ž" => "ž", "Š" => "š");
return
strtolower(strtr($string,$low));
}

?>
up
0
marco at recchiuti dot it
17 years ago
Maybe it is not so elegant, but it Works.
It's just a fast Idea and it is what I need.
Any hacks for other characters (link !, ? etc etc) should help.

function RemoveShouting($string)
{
$frase = "";
$astri = explode(".", $string);
foreach ($astri as $elem)
$frase .= " ".ucfirst(trim(strtolower($elem))).". ";

return trim($frase);
}

Cheers!
M
up
-1
Patrick
18 years ago
If you're considering using the below unhtmlentities function from phpContrib, I would suggest this one as an alternative:

<?php
function unhtmlentities($string)
{
// replace numeric entities
$string = preg_replace('~&#x([0-9a-f]+);~ei', 'chr(hexdec("\\1"))', $string);
$string = preg_replace('~&#([0-9]+);~e', 'chr(\\1)', $string);
// replace literal entities
$trans_tbl = get_html_translation_table(HTML_ENTITIES);
$trans_tbl = array_flip($trans_tbl);
return
strtr($string, $trans_tbl);
}
?>

That was copied exactly from the html_entity_decode manual page. It'll handle numeric entities correctly, the below function won't.
up
-2
bkimble at ebaseweb dot com
21 years ago
Heres a small function I wrote to stop people from submitting data that is ALL IN CAPS SO THEY CAN GET MORE ATTENTION THAT THE REST OF THE USER SUBMITTED DATA on my website :) If you can make it better, by all means do so. This function splits up words delimited by a space, and makes only the first letter of each word capitalized. You can easily modify it so it's only the very first word of the string. I've also added some exceptions so you don't make things like roman numerals look like "Iii" or "Xcmii" or something.

function RemoveShouting($string)
{
$lower_exceptions = array(
"to" => "1", "a" => "1", "the" => "1", "of" => "1"
);

$higher_exceptions = array(
"I" => "1", "II" => "1", "III" => "1", "IV" => "1",
"V" => "1", "VI" => "1", "VII" => "1", "VIII" => "1",
"XI" => "1", "X" => "1"
);

$words = split(" ", $string);
$newwords = array();
foreach ($words as $word)
{
if (!$higher_exceptions[$word]) $word = strtolower($word);
if (!$lower_exceptions[$word]) $word[0] = strtoupper($word[0]);
array_push($newwords, $word);
}
return join(" ", $newwords);
}

BK
up
-3
RCube
13 years ago
To convert an entire array to lower, I prefer this method;

<?php
function arraytolower(array $array, $round = 0){
return
unserialize(strtolower(serialize($array)));
}
?>

3 lines of code seem a lot less overhead than 10-40.
If there's any intrinsic problem with this method, please post it.
up
-4
kmcdermott at perimeterinstitute dot ca
19 years ago
To do case insensitive comparisons in a database, strtolower() can be a quick and dirty solution:

$Sql = "SELECT * FROM tablename WHERE LOWER(column_name) = '".strtolower($my_var)."'";
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