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    strtolower

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

    strtolower — 将字符串转化为小写

    说明

    strtolower(string $string): string

    将 string 中所有的 ASCII 字母字符转换为小写并返回。

    "A"（0x41）到 "Z"（0x5a）范围内的字节会通过将每个字节值加 32 转为相应的小写字母。

    这可用于转换用 UTF-8 编码的字符串中的 ASCII 字符，但会忽略多字节 UTF-8 字符。要转换多字节非 ASCII 字符，请使用 mb_strtolower()。

    参数

    string

    输入字符串。

    返回值

    返回转换后的小写字符串。

    更新日志

    版本 说明
    8.2.0 大小写转换不在依赖于使用 setlocale() 设置的区域。只会转换 ASCII 字符。

    示例

    示例 #1 strtolower() 示例

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

    注释

    注意: 此函数可安全用于二进制对象。

    参见

    add a note add a note

    User Contributed Notes 16 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
    35
    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
    24
    helvete at bahno dot net
    9 years ago
    It is worth noting that
    <?php
    var_dump    (strtolower(null))
    ?>
    returns:
    string(0) ""
    up
    11
    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
    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
    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
    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
    0
    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
    0
    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
    -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
    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
    -6
    leha_grobov
    15 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);
    }
    ?>
    up
    -5
    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)."'";
    up
    -11
    spiceee ddotty spiceee com
    18 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">
    up
    -12
    Daniel Klein
    8 years ago
    When the locale is set to "utf8" or "C" I can't get strtolower() to convert accented characters encoded as UTF-8, so here is my workaround.

    <?php
    function tolower($string) {
      if (    $old_locale = setlocale(LC_CTYPE, 0)) {
            // 'fr_FR.ISO-8859-1' for *nix, 'French_France.1252' fallback for Windows
            if ($newlocale = setlocale(LC_CTYPE, 'fr_FR.ISO-8859-1', 'French_France.1252')) {
              preg_match('/\.(?<encoding>.+)$/', $newlocale, $match);
              $string = utf8_encode(strtolower(utf8_decode($string)));
        }
            setlocale(LC_CTYPE, $old_locale);
      }
      return     $string;
    }

    print(    tolower('DÉJÀ-VU'));  // prints déjà-vu
    ?>

    Change the language-country codes if you want some language other than French.
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