問題描述

我也有帶有變音符號的 UTF-8 文本，想檢查該文本的第一個字母是大寫還是小寫.如何做到這一點?

I have texts in UTF-8 with diacritic characters also, and would like to check if first letter of this text is upper case or lower case. How to do this?

推薦答案

我認為，與此處發布的其他解決方案相比，進行 preg_ 調用是最直接、簡潔和可靠的調用.

It is my opinion that making a preg_ call is the most direct, concise, and reliable call versus the other posted solutions here.

echo preg_match('~^p{Lu}~u', $string) ? 'upper' : 'lower';

我的模式分解:

~      # starting pattern delimiter 
^      #match from the start of the input string
p{Lu} #match exactly one uppercase letter (unicode safe)
~      #ending pattern delimiter 
u      #enable unicode matching

ctype_ 和 <時請注意'a' 在這一系列測試中失敗了.

Please take notice when ctype_ and < 'a' fail with this battery of tests.

代碼:(演示)

$tests = ['aa', 'Bbbbb', 'éé', 'iou', 'Δδ'];

foreach ($tests as $test) {
    echo "
{$test}:";
    echo "
	PREG:  " , preg_match('~^p{Lu}~u', $test)      ? 'upper' : 'lower';
    echo "
	CTYPE: " , ctype_upper(mb_substr($test, 0, 1))  ? 'upper' : 'lower';
    echo "
	< a:   " , mb_substr($test, 0, 1) < 'a'         ? 'upper' : 'lower';

    $chr = mb_substr ($test, 0, 1, "UTF-8");
    echo "
	MB:    " , mb_strtoupper($chr, "UTF-8") == $chr ? 'upper' : 'lower';
}

輸出:

aa:
    PREG:  lower
    CTYPE: lower
    < a:   lower
    MB:    lower
Bbbbb:
    PREG:  upper
    CTYPE: upper
    < a:   upper
    MB:    upper
éé:               <-- trouble
    PREG:  upper
    CTYPE: lower  <-- uh oh
    < a:   lower  <-- uh oh
    MB:    upper
iou:
    PREG:  lower
    CTYPE: lower
    < a:   lower
    MB:    lower
Δδ:               <-- extended beyond question scope
    PREG:  upper  <-- still holding up
    CTYPE: lower
    < a:   lower
    MB:    upper  <-- still holding up

如果有人需要區分大寫字母、小寫字母和非字母，請參閱這篇文章.

If anyone needs to differentiate between uppercase letters, lowercase letters, and non-letters see this post.

這可能把這個問題的范圍擴展得太遠了，但如果你輸入的字符特別松散(它們可能不存在于Lu可以處理的類別中)，你可能需要檢查一下第一個字符有大小寫變體:

It may be extending the scope of this question too far, but if your input characters are especially squirrelly (they might not exist in a category that Lu can handle), you may want to check if the first character has case variants:

p{L&} 或 p{Cased_Letter}:存在大小寫變體的字母(Ll、Lu 和 Lt 的組合).

p{L&} or p{Cased_Letter}: a letter that exists in lowercase and uppercase variants (combination of Ll, Lu and Lt).

• 來源:https://www.regular-expressions.info/unicode.html

要包含帶有 SMALL 變體的羅馬數字(數字字母")，如有必要，您可以將該額外范圍添加到模式中.

To include Roman Numerals ("Number Letters") with SMALL variants, you can add that extra range to the pattern if necessary.

https://www.fileformat.info/info/unicode/category/Nl/list.htm

代碼:(演示)

echo preg_match('~^[p{Lu}x{2160}-x{216F}]~u', $test) ? 'upper' : 'not upper';

這篇關于PHP中如何判斷字母是大寫還是小寫?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！

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