PHP 5.6.0 released

strtolower

(PHP 4, PHP 5)

strtolowerMake a string lowercase

Description

string strtolower ( string $str )

Returns string with all alphabetic characters converted to lowercase.

Note that 'alphabetic' is determined by the current locale. This means that in i.e. the default "C" locale, characters such as umlaut-A (Ä) will not be converted.

Parameters

str

The input string.

Return Values

Returns the lowercased string.

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

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User Contributed Notes 17 notes

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26
marcin at maydesign dot pl
4 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
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13
coder at bulgaria dot bg
5 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
?>
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3
bkimble at ebaseweb dot com
11 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
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3
dbers26 at gmail dot com
5 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
)
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3
rodrigoATsistemasparainternetDOTcomDOTbr
5 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
?>
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5
leha_grobov
5 years ago
the strtolower version to support most amount of languages including russian, french and so on:

<?php
function strtolower_utf8($string){
 
$convert_to = array(
   
"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u",
   
"v", "w", "x", "y", "z", "à", "á", "â", "ã", "ä", "å", "æ", "ç", "è", "é", "ê", "ë", "ì", "í", "î", "ï",
   
"ð", "ñ", "ò", "ó", "ô", "õ", "ö", "ø", "ù", "ú", "û", "ü", "ý", "а", "б", "в", "г", "д", "е", "ё", "ж",
   
"з", "и", "й", "к", "л", "м", "н", "о", "п", "р", "с", "т", "у", "ф", "х", "ц", "ч", "ш", "щ", "ъ", "ы",
   
"ь", "э", "ю", "я"
 
);
 
$convert_from = array(
   
"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U",
   
"V", "W", "X", "Y", "Z", "À", "Á", "Â", "Ã", "Ä", "Å", "Æ", "Ç", "È", "É", "Ê", "Ë", "Ì", "Í", "Î", "Ï",
   
"Ð", "Ñ", "Ò", "Ó", "Ô", "Õ", "Ö", "Ø", "Ù", "Ú", "Û", "Ü", "Ý", "А", "Б", "В", "Г", "Д", "Е", "Ё", "Ж",
   
"З", "И", "Й", "К", "Л", "М", "Н", "О", "П", "Р", "С", "Т", "У", "Ф", "Х", "Ц", "Ч", "Ш", "Щ", "Ъ", "Ъ",
   
"Ь", "Э", "Ю", "Я"
 
);

  return
str_replace($convert_from, $convert_to, $string);
}
?>
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1
Patrick
8 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.
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1
fackelkind
8 years ago
Nifty? :D

<?php
       
function is_lowercase ($str){
                return (
$str == strtolower ($str));
        }
?>
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2
rok dot kralj at gmail dot com
7 years ago
Slovenian characters

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

?>
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1
spiceee ddotty spiceee com
8 years ago
If you ever need to strtolower a string with href tags on it and doesn't want to mess with the characters inside a tag, this is for you.

<?php

function loweroutsidetags ($str) {
   
$chars = preg_split ("//", $str);
   
$tolower = true;
   
$str = '';

    foreach (
$chars as $k) {
        if (
$k == '<') { $tolower = false; }
        if (
$tolower) { $k = strtolower ($k); }
       
$str .= $k;   
        if (
$k == '>') { $tolower = true; }
    }
    return
$str;
}

?>

this:
echo loweroutsidetags('aALalala <a href="?q=CASEsENSITIVINESSinURLSareSTUPID">')

will give:
aalalala <a href="?q=CASEsENSITIVINESSinURLSareSTUPID">
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1
on at niepodam dot pl
2 years ago
If the input string is in different language that server locale, then you should use mb_strtolower() function.
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1
kmcdermott at perimeterinstitute dot ca
9 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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1
patricia at steuerungb dot de
6 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.
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0
RCube
3 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.
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0
marco at recchiuti dot it
7 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
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0
mhuggins57 at yahoo dot com
9 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.
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-1
spider_poison at hotmail dot com
9 months ago
PT-BR lower case ...

function minuscula($str){
    return preg_replace(array("/[À-Å]/","/[È-Ë]/","/[Ì-Ï]/","/[Ò-ÖØ]/","/[Ù-Ü]/"),array("a","e","i","o","u"),$str);
}
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