php - 如何反转 Unicode 字符串

Question

它在 comment to an answer to this question 中被暗示PHP 不能反转 Unicode 字符串。

As for Unicode, it works in PHP because most apps process it as binary. Yes, PHP is 8-bit clean. Try the equivalent of this in PHP: perl -Mutf8 -e 'print scalar reverse("ほげほげ")' You will get garbage, not "げほげほ". – jrockway

不幸的是，PHP 的 unicode 支持 atm 充其量是“缺乏”是正确的。这将 hopefully change drastically with PHP6 .

PHP MultiByte functions确实提供了处理 unicode 所需的基本功能，但它不一致并且确实缺少很多功能。其中之一是反转字符串的函数。

我当然想无缘无故地覆盖这段文字，然后看看是否可行。我创建了一个函数来完成反转此 Unicode 文本这一巨大的复杂任务，因此您可以在 PHP6 之前放松一下。

测试代码:

$enc = 'UTF-8';
$text = "ほげほげ";
$defaultEnc = mb_internal_encoding();

echo "Showing results with encoding $defaultEnc.\n\n";

$revNormal = strrev($text);
$revInt = mb_strrev($text);
$revEnc = mb_strrev($text, $enc);

echo "Original text is: $text .\n";
echo "Normal strrev output: " . $revNormal . ".\n";
echo "mb_strrev without encoding output: $revInt.\n";
echo "mb_strrev with encoding $enc output: $revEnc.\n";

if (mb_internal_encoding($enc)) {
    echo "\nSetting internal encoding to $enc from $defaultEnc.\n\n";

    $revNormal = strrev($text);
    $revInt = mb_strrev($text);
    $revEnc = mb_strrev($text, $enc);

    echo "Original text is: $text .\n";
    echo "Normal strrev output: " . $revNormal . ".\n";
    echo "mb_strrev without encoding output: $revInt.\n";
    echo "mb_strrev with encoding $enc output: $revEnc.\n";

} else {
    echo "\nCould not set internal encoding to $enc!\n";
}

Answer 1

这是使用正则表达式的另一种方法:

function utf8_strrev($str){
 preg_match_all('/./us', $str, $ar);
 return implode(array_reverse($ar[0]));
}