替换多个换行符，制表符和空格

Question

I want to replace multiple newline characters with one newline character, and multiple spaces with a single space.

I tried preg_replace("/\\n\\n+/", "\\n", $text); and failed!

I also do this job on the $text for formatting.

$text = wordwrap($text, 120, '<br/>', true);
$text = nl2br($text);

$text is a large text taken from user for BLOG, and for a better formatting I use wordwrap.

Answer 1

In theory, you regular expression does work, but the problem is that not all operating system and browsers send only \\n at the end of string. Many will also send a \\r.

Try:

I've simplified this one:

preg_replace("/(\r?\n){2,}/", "\n\n", $text);

And to address the problem of some sending \\r only:

preg_replace("/[\r\n]{2,}/", "\n\n", $text);

Based on your update:

// Replace multiple (one ore more) line breaks with a single one.
$text = preg_replace("/[\r\n]+/", "\n", $text);

$text = wordwrap($text,120, '<br/>', true);
$text = nl2br($text);

Answer 2

Use \\R (which represents any line ending sequence):

$str = preg_replace('#\R+#', '</p><p>', $str);

It was found here: Replacing two new lines with paragraph tags

PHP documentation about Escape sequences :

\\R (line break: matches \\n, \\r and \\r\\n)

Answer 3

This is the answer, as I understand the question:

// Normalize newlines
preg_replace('/(\r\n|\r|\n)+/', "\n", $text);
// Replace whitespace characters with a single space
preg_replace('/\s+/', ' ', $text);

---

This is the actual function that I use to convert new lines to HTML line break and paragraph elements:

/**
 *
 * @param string $string
 * @return string
 */
function nl2html($text)
{
    return '<p>' . preg_replace(array('/(\r\n\r\n|\r\r|\n\n)(\s+)?/', '/\r\n|\r|\n/'),
            array('</p><p>', '<br/>'), $text) . '</p>';
}

Answer 4

You need the multiline modifier to match multiple lines:

preg_replace("/PATTERN/m", "REPLACE", $text);

Also in your example you seem to be replacing 2+ newlines with exactly 2, which isn't what your question indicates.

Answer 5

I tried all of above, but it didn't work for me. Then I created some long way to resolve that issue...

Before :

echo nl2br($text);

After :

$tempData = nl2br($text);
$tempData = explode("<br />",$tempData);

foreach ($tempData as $val) {
   if(trim($val) != '')
   {
      echo $val."<br />";
   }
}

And it's worked for me.. I wrote here because, if somebody came here to find answer like me.

Answer 6

如果您只想用单个选项卡替换多个选项卡，请使用以下代码。

preg_replace("/\s{2,}/", "\t", $string);

Answer 7

I would suggest something like this:

preg_replace("/(\R){2,}/", "$1", $str);

This will take care of all the Unicode newline characters.

Answer 8

更换头部和字符串或文档的末尾！

preg_replace('/(^[^a-zA-Z]+)|([^a-zA-Z]+$)/','',$match);

Answer 9

I have dealt with strip_tags function in PHP and had some problems like: after having a linebreak then appear a new line with some spaces and then a new linebreak appear continuously ...etc. without any rule :(.

This is my solution for dealing with strip_tags

Replace multiple spaces to one, multiple linebreaks to single linebreak

function cleanHtml($html)
{
    // Clean code into script tags
    $html = preg_replace('#<script(.*?)>(.*?)</script>#is', '', $html);

    // Clean code into style tags
    $html = preg_replace('/<\s*style.+?<\s*\/\s*style.*?>/si', '', $html );

    // Strip HTML
    $string = trim(strip_tags($html));

    // Replace multiple spaces on each line (keep linebreaks) with single space
    $string = preg_replace("/[[:blank:]]+/", " ", $string); // (*)

    // Replace multiple spaces of all positions (deal with linebreaks) with single linebreak
    $string = preg_replace('/\s{2,}/', "\n", $string); // (**)
    return $string;
}

Keywords are (*) and (**).

Answer 10

尝试这个：

preg_replace("/[\r\n]*/", "\r\n", $text);