PHP preg_replace替换换行没什么用

I have a text field retrieved by a Solr query that contains the body of an email. I am trying to replace embedded line breaks with paragraph tags via PHP like so:

$text = $item->Body[0];
$new_line = array("
", "
", "");
preg_replace($new_line,'</p><p>',$text);
echo $text;

When I show the result in my IDE/debugger the newline characters are not replaced and are still there:

I have been going through threads on this site trying patterns suggested by different people including "/\s+/" and PHP_EOL and "/( || )/" and nothing works. What am I doing wrong?

You are missing the delimiter around your regex strings and you are not assigning the value.
You can also reduce your regex:

$text = preg_replace("/?
|/", '</p><p>', $text);

You might want switch to the multibyte safe version. They work with Unicode and you don't need delimiters there ;)

$text = mb_ereg_replace("?
|", '</p><p>', $text);

Wait...dumb question! Should be

$text = preg_replace($new_line,'</p><p>',$text);

Sorry, I normally code in Perl and am used to the $text =~ construction.

preg_replace is for regular expressions. What you want is a simple string replacement, so you should use str_replace

$text = $item->Body[0];
$new_line = array("
", "
", "");
$text = str_replace($new_line,'</p><p>',$text);
echo $text;