Replace multiple newlines, tabs, and spaces

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\",

Answer 1

Replace the head and the end of string or document!

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

Answer 2

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 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

I would suggest something like this:

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

This will take care of all the Unicode newline characters.