strtolower

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

strtolower — 文字列を小文字にする

説明

strtolower(string $string): string

string の、ASCII のアルファベット部分をすべて小文字にして返します｡

"A" (0x41) から "Z" (0x5a) までの範囲のバイト列は、それぞれのバイト値に 32 を加えることによって対応する小文字に変換されます。

マルチバイトの UTF-8 文字は無視されるので、 UTF-8 でエンコードされた文字列中にある ASCII 文字を変換する際も、このやり方が使えます。マルチバイトの ASCII でない文字を変換するには、 mb_strtolower() を使います。

パラメータ

string: 入力文字列。

戻り値

小文字に変換した文字列を返します。

変更履歴

バージョン	説明
8.2.0	ケース変換は、setlocale() で設定されたロケールに依存しなくなりました。 ASCII 文字のみが変換されます。

例

例1 strtolower() の例

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

注意

注意: この関数はバイナリデータに対応しています。

参考

strtoupper() - 文字列を大文字にする
ucfirst() - 文字列の最初の文字を大文字にする
ucwords() - 文字列の各単語の最初の文字を大文字にする
mb_strtolower() - 文字列を小文字にする

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User Contributed Notes 13 notes

down

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

down

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

?>

down

helvete at bahno dot net ¶

9 years ago

It is worth noting that 
<?php 
var_dump(strtolower(null))
?>
returns: 
string(0) ""

down

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

)

down

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.

down

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.

down

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
?>

down

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));
    }

?>

down

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

down

-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.

down

-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

down

-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.

down

-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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