使用 PHP 中的普通 substr() 函数，您可以决定要“开始”切割字符串的位置，以及设置长度。长度可能是用得最多的，但在这种情况下，我需要从头开始剪掉大约 120 个字符。问题是我需要保持字符串中的 html 完好无损，并且只剪切标签中的实际文本。

我为它找到了一些自定义函数，但我还没有找到一个允许您设置起点的函数，例如。您要从哪里开始剪弦。

这是我找到的一个:Using PHP substr() and strip_tags() while retaining formatting and without breaking HTML

所以，我基本上需要一个 substr() 函数，它的工作方式与原始函数完全相同，只是保持格式化。

有什么建议吗？

要修改的示例内容:

<p>Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going <a href="#">through the cites</a> of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus</p> <p>Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the <strong>Renaissance</strong>. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.</p>

从一开始砍掉5之后:

<p>ary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going <a href="#">through the cites</a> of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus</p> <p>Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the <strong>Renaissance</strong>. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.</p>

还有 5 个开头和结尾:

<p>ary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going <a href="#">through the cites</a> of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus</p> <p>Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the <strong>Renaissance</strong>. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.1</p>

是的，你明白我的意思了吗？

如果它要在一个单词的中间停止切割，我更希望它切割整个单词，但这并不是特别重要。

** 编辑:** 固定引号。

最佳答案

您所问的内容涉及很多复杂问题(本质上，在给定 string 偏移量的情况下生成有效的 html 子集)，如果您以这种方式重新表述您的问题，那真的会更好它表示为您要保留的文本字符的数量，而不是剪切其中包含 html 的任意字符串。如果这样做，这个问题就会变得容易得多，因为您可以使用真正的 HTML 解析器。您无需担心:

• 不小心将元素切成两半。
• 不小心将实体切成两半。
• 不计算元素内的文本。
• 确保字符实体算作单个字符。
• 确保所有元素都正确关闭。
• 确保您不会破坏字符串，因为您在 utf-8 字符串上使用 substr()。

使用正则表达式(使用 u 标志)和 mb_substr() 和标签堆栈(我已经以前做过)，但是有很多边缘情况，你通常会遇到困难。

但是，DOM 解决方案相当简单:遍历所有文本节点，计算字符串长度，然后根据需要删除或子字符串化它们的文本内容。下面的代码执行此操作:

$html = <<<'EOT'
<p>Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going <a href="#">through the cites</a> of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus</p> <p>Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the <strong>Renaissance</strong>. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.</p>
EOT;

function substr_html($html, $start, $length=null, $removeemptyelements=true) {
    if (is_int($length)) {
        if ($length===0) return '';
        $end = $start + $length;
    } else {
        $end = null;
    }
    $d = new DOMDocument();
    $d->loadHTML('<html><head><meta http-equiv="content-type" content="text/html;charset=utf-8"><title></title></head><body>'.$html.'</body>');
    $body = $d->getElementsByTagName('body')->item(0);
    $dxp = new DOMXPath($d);
    $t_start = 0; // text node's start pos relative to all text
    $t_end   = null; // text node's end pos relative to all text

    // copy because we may modify result of $textnodes
    $textnodes = iterator_to_array($dxp->query('/descendant::*/text()', $body));

// PHP 5.2 doesn't seem to implement Traversable on DOMNodeList,
// so `iterator_to_array()` won't work. Use this instead:
// $textnodelist = $dxp->query('/descendant::*/text()', $body);
// $textnodes = array();
// for ($i = 0; $i < $textnodelist->length; $i++) {
//  $textnodes[] = $textnodelist->item($i);
//}
//unset($textnodelist);

    foreach($textnodes as $text) {
        $t_end = $t_start + $text->length;
        $parent = $text->parentNode;
        if ($start >= $t_end || ($end!==null && $end < $t_start)) {
            $parent->removeChild($text);
        } else {
            $n_offset = max($start - $t_start, 0);
            $n_length = ($end===null) ? $text->length : $end - $t_start;
            if (!($n_offset===0 && $n_length >= $text->length)) {
                $substr = $text->substringData($n_offset, $n_length);
                if (strlen($substr)) {
                    $text->deleteData(0, $text->length);
                    $text->appendData($substr);
                } else {
                    $parent->removeChild($text);
                }
            }
        }

        // if removing this text emptied the parent of nodes, remove the node!
        if ($removeemptyelements && !$parent->hasChildNodes()) {
            $parent->parentNode->removeChild($parent);
        }

        $t_start = $t_end;
    }
    unset($textnodes);
    $newstr = $d->saveHTML($body);

    // mb_substr() is to remove <body></body> tags
    return mb_substr($newstr, 6, -7, 'utf-8');
}


echo substr_html($html, 480, 30);

这将输出:

<p> of "de Finibus</p> <p>Bonorum et Mal</p>

请注意，您的“子字符串”跨越多个 p 元素这一事实不会造成混淆。

关于允许您设置起点和终点并保持 HTML 格式的 PHP substr() 函数？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14140596/