mb_convert_case()

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

对字符串进行大小写转换

说明

mb_convert_case(string $str,int $mode[,string $encoding= mb_internal_encoding()]): string

对一个string进行大小写转换，转换模式由$mode指定。

参数

$str: 要被转换的string。
$mode: 转换的模式。它可以是MB_CASE_UPPER、MB_CASE_LOWER和MB_CASE_TITLE的其中一个。
$encoding: $encoding参数为字符编码。如果省略，则使用内部字符编码。

返回值

按$mode指定的模式转换$string大小写后的版本。

Unicode

和类似strtolower()、strtoupper()的标准大小写转换函数相比，大小写转换的执行根据 Unicode 字符属性的基础。因此此函数的行为不受语言环境（locale）设置的影响，能够转换任意具有“字母”属性的字符，例如元音变音A（Ä）。

更多关于 Unicode 属性的信息，请查看» http://www.unicode.org/unicode/reports/tr21/。

范例

mb_convert_case()例子

<?php
$str = "mary had a Little lamb and she loved it so";
$str = mb_convert_case($str, MB_CASE_UPPER, "UTF-8");
echo $str; // 输出 MARY HAD A LITTLE LAMB AND SHE LOVED IT SO
$str = mb_convert_case($str, MB_CASE_TITLE, "UTF-8");
echo $str; // 输出 Mary Had A Little Lamb And She Loved It So
?>

非拉丁 UTF-8 文本的mb_convert_case()例子

<?php
$str = "Τάχιστη αλώπηξ βαφής ψημένη γη, δρασκελίζει υπέρ νωθρού κυνός";
$str = mb_convert_case($str, MB_CASE_UPPER, "UTF-8");
echo $str; // 输出 ΤΆΧΙΣΤΗ ΑΛΏΠΗΞ ΒΑΦΉΣ ΨΗΜΈΝΗ ΓΗ, ΔΡΑΣΚΕΛΊΖΕΙ ΥΠΈΡ ΝΩΘΡΟΎ ΚΥΝΌΣ
$str = mb_convert_case($str, MB_CASE_TITLE, "UTF-8");
echo $str; // 输出 Τάχιστη Αλώπηξ Βαφήσ Ψημένη Γη, Δρασκελίζει Υπέρ Νωθρού Κυνόσ
?>

参见

mb_strtolower()使字符串小写
mb_strtoupper()使字符串大写
strtolower()将字符串转化为小写
strtoupper()将字符串转化为大写
ucfirst()将字符串的首字母转换为大写
ucwords()将字符串中每个单词的首字母转换为大写

as the previouly posted version of this function doesn't handle UTF-8 characters, I simply tried to replace ucfirst to mb_convert_case, but then any previous case foldings were lost while looping through delimiters. 
So I decided to do an mb_convert_case on the input string (it also deals with words is uppercase wich may also be problematic when doing case-sensitive search), and do the rest of checking after that.
As with mb_convert_case, words are capitalized, I also added lowercase convertion for the exceptions, but, for the above mentioned reason, I left ucfirst unchanged.
Now it works fine for utf-8 strings as well, except for string delimiters followed by an UTF-8 character ("Mcádám" is unchanged, while "mcdunno's" is converted to "McDunno's" and "ökrös-TÓTH éDUa" in also put in the correct form)
I use it for checking user input on names and addresses, so exceptions list contains some hungarian words too.
<?php
function titleCase($string, $delimiters = array(" ", "-", ".", "'", "O'", "Mc"), $exceptions = array("út", "u", "s", "és", "utca", "tér", "krt", "körút", "sétány", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX", "X", "XI", "XII", "XIII", "XIV", "XV", "XVI", "XVII", "XVIII", "XIX", "XX", "XXI", "XXII", "XXIII", "XXIV", "XXV", "XXVI", "XXVII", "XXVIII", "XXIX", "XXX" )) {
    /*
    * Exceptions in lower case are words you don't want converted
    * Exceptions all in upper case are any words you don't want converted to title case
    *  but should be converted to upper case, e.g.:
    *  king henry viii or king henry Viii should be King Henry VIII
    */
    $string = mb_convert_case($string, MB_CASE_TITLE, "UTF-8");
    foreach ($delimiters as $dlnr => $delimiter){
        $words = explode($delimiter, $string);
        $newwords = array();
        foreach ($words as $wordnr => $word){
        
            if (in_array(mb_strtoupper($word, "UTF-8"), $exceptions)){
                // check exceptions list for any words that should be in upper case
                $word = mb_strtoupper($word, "UTF-8");
            }
            elseif (in_array(mb_strtolower($word, "UTF-8"), $exceptions)){
                // check exceptions list for any words that should be in upper case
                $word = mb_strtolower($word, "UTF-8");
            }
            
            elseif (!in_array($word, $exceptions) ){
                // convert to uppercase (non-utf8 only)
               
                $word = ucfirst($word);
                
            }
            array_push($newwords, $word);
        }
        $string = join($delimiter, $newwords);
    }//foreach
    return $string;
} 
?>

MB_CASE_TITLE doesn't change letters in quotation marks.
Example:
mb_convert_case('AAA "aaa"', MB_CASE_TITLE); 
// Result: Aaa "aaa"

For my case following did the work to capitalize UTF-8 encoded string. 
function capitalize($str, $encoding = 'UTF-8') {
  return mb_strtoupper(mb_substr($str, 0, 1, $encoding), $encoding) . mb_strtolower(mb_substr($str, 1, mb_strlen($str), $encoding), $encoding);
}

For CZECH characters:
<?php
$text = mb_convert_case($text, MB_CASE_LOWER, "Windows-1251");
?>
The right encoding Windows-1250 is not valid (see the list mb_list_encodings), but Windows-1251 will do the same 100%. The function strtolower() ignores czech characters with diacritics.

for turkish simple:
$str = mb_convert_case(str_replace(['i','I'], ['İ','ı'], $str), MB_CASE_TITLE,"UTF-8");

Building upon Justin's and Alex's work... 
This function allows you to specify which delimiter(s) to explode on (not just the default space). Now you can correctly capitalize Irish names and hyphenated words (if you want)!
<?php
function titleCase($string, $delimiters = array(" ", "-", "O'"), $exceptions = array("to", "a", "the", "of", "by", "and", "with", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX", "X")) {
    /*
    * Exceptions in lower case are words you don't want converted
    * Exceptions all in upper case are any words you don't want converted to title case
    *  but should be converted to upper case, e.g.:
    *  king henry viii or king henry Viii should be King Henry VIII
    */
    foreach ($delimiters as $delimiter){
        $words = explode($delimiter, $string);
        $newwords = array();
        foreach ($words as $word){
            if (in_array(strtoupper($word), $exceptions)){
                // check exceptions list for any words that should be in upper case
                $word = strtoupper($word);
            } elseif (!in_array($word, $exceptions)){
                // convert to uppercase
                $word = ucfirst($word);
            }
            array_push($newwords, $word);
        }
        $string = join($delimiter, $newwords);
    }
    return $string;
}
?>

This is a variation of mb_convert_case that works only for UTF-8 strings and that will not convert to lowercase anything.
This avoids turning "AAA aaa" into "Aaa Aaa"; it maps "AAA aaa" into ""AAA Aaa" instead.
<?php
function mb_convert_case_utf8_variation($s) {
  $arr = preg_split("//u", $s, -1, PREG_SPLIT_NO_EMPTY);
  $result = "";
  $mode = false;
  foreach ($arr as $char) {
    $res = preg_match(
      '/\\p{Mn}|\\p{Me}|\\p{Cf}|\\p{Lm}|\\p{Sk}|\\p{Lu}|\\p{Ll}|'.
      '\\p{Lt}|\\p{Sk}|\\p{Cs}/u', $char) == 1;
    if ($mode) {
      if (!$res)
        $mode = false;
    }
    elseif ($res) {
      $mode = true;
      $char = mb_convert_case($char, MB_CASE_TITLE, "UTF-8");
    }
    $result .= $char;
  }
  return $result;
}
?>

for turkish language I => i and i => I conversion is a problem. It must be I => ı and i => İ so my simple solution is
  public function title_case_turkish($str){
 
    $str = str_replace("i", "İ", $str);
    $str = str_replace("I", "ı", $str);
    $str = mb_convert_case($str, MB_CASE_TITLE,"UTF-8");
    return $str;
  }