Remove line breaks with regex

remove-line-breaks-with-regex.php

<?php

$string = 'This is a new paragraph with
arbitrarily inserted newlines
at a certain width. To keep
these from turning into <br>s,
we want to replace them the right
way.

When there is a double new-line,
then we know that it really is a
new paragraph, and it is OK to keep
both newlines together.';

$content_without_line_breaks = preg_replace( '/(^|[^\n\r])[\r\n](?![\n\r])/', '$1 ', $string );