将多字节字符串截断为n个字符 [英] Truncate a multibyte String to n chars

问题描述

我正在尝试使此方法在字符串过滤器中起作用:

I am trying to get this method in a String Filter working:

public function truncate($string, $chars = 50, $terminator = ' …');

我希望如此

$in  = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWYXZ1234567890";
$out = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUV …";

还有这个

$in  = "âãäåæçèéêëìíîïðñòóôõö÷øùúûüýþÿĀāĂ㥹ĆćĈĉĊċČčĎďĐđĒēĔĕĖėĘęĚěĜĝ";
$out = "âãäåæçèéêëìíîïðñòóôõö÷øùúûüýþÿĀāĂ㥹ĆćĈĉĊċČčĎďĐđ …";

即$chars减去$terminator字符串的字符.

That is $chars minus the chars of the $terminator string.

此外，该过滤器应该在$chars限制以下的第一个单词边界处剪切，例如

In addition, the filter is supposed to cut at the first word boundary below the $chars limit, e.g.

$in  = "Answer to the Ultimate Question of Life, the Universe, and Everything.";
$out = "Answer to the Ultimate Question of Life, the …";

我很确定这可以通过以下步骤进行操作

I am pretty certain this should work with these steps

• 从最大字符数中减去终止符中的字符数
• 验证该字符串是否长于计算出的限制，或将其保留原样返回
• 找到字符串中最后一个空格字符，该字符低于计算的限制以获取单词边界
• 在最后一个空格处剪切字符串，或者在找不到最后一个空格的情况下计算出限制
• 将终止符附加到字符串
• 返回字符串

但是，我现在尝试了str*和mb_*函数的各种组合，但是都产生了错误的结果.这不是那么困难，所以我显然缺少了一些东西.有人会为此或共享一个可行的实施方案吗?还是将我指向可以最终了解如何实现此目标的资源.

However, I have tried various combinations of str* and mb_* functions now, but all yielded wrong results. This can't be so difficult, so I am obviously missing something. Would someone share a working implementation for this or point me to a resource where I can finally understand how to do it.

谢谢

P.S.是的，我已经检查过 https://stackoverflow.com/search?q=truncate+string+php 之前:)

P.S. Yes, I have checked https://stackoverflow.com/search?q=truncate+string+php before :)

推荐答案

尝试一下:

function truncate($string, $chars = 50, $terminator = ' …') {
    $cutPos = $chars - mb_strlen($terminator);
    $boundaryPos = mb_strrpos(mb_substr($string, 0, mb_strpos($string, ' ', $cutPos)), ' ');
    return mb_substr($string, 0, $boundaryPos === false ? $cutPos : $boundaryPos) . $terminator;
}

但是您需要确保正确设置内部编码.

But you need to make sure that your internal encoding is properly set.

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