PHP Unconference Europe 2015

nl2br

(PHP 4, PHP 5)

nl2br在字符串所有新行之前插入 HTML 换行标记

说明

string nl2br ( string $string [, bool $is_xhtml = true ] )

在字符串 string 所有新行之前插入 '<br />' 或 '<br>',并返回。

参数

string

输入字符串。

is_xhtml

是否使用 XHTML 兼容换行符。

返回值

返回调整后的字符串。

范例

Example #1 nl2br() 使用范例

<?php
echo nl2br("foo isn't\n bar");
?>

以上例程会输出:

foo isn't<br />
 bar

Example #2 使用 is_xhtml 生成合法的 HTML 标记

<?php
echo nl2br("Welcome\r\nThis is my HTML document"false);
?>

以上例程会输出:

Welcome<br>
This is my HTML document

Example #3 各种换行分隔符

<?php
$string 
"This\r\nis\n\ra\nstring\r";
echo 
nl2br($string);
?>

以上例程会输出:

This<br />
is<br />
a<br />
string<br />

更新日志

版本 说明
5.3.0 新增可选的 is_xhtml 参数。
4.0.5 nl2br() 成为 XHTML 兼容的操作。所有的旧版本都会在 string 的新行之前插入 '<br>' 而不是 '<br />'。

参见

add a note add a note

User Contributed Notes 11 notes

up
27
N/A
6 years ago
Here's a more simple one:

<?php
/**
* Convert BR tags to nl
*
* @param string The string to convert
* @return string The converted string
*/
function br2nl($string)
{
    return
preg_replace('/\<br(\s*)?\/?\>/i', "\n", $string);
}
?>

Enjoy
up
19
CGameProgrammer at gmail dot com
9 years ago
It's important to remember that this function does NOT replace newlines with <br> tags. Rather, it inserts a <br> tag before each newline, but it still preserves the newlines themselves! This caused problems for me regarding a function I was writing -- I forgot the newlines were still being preserved.

If you don't want newlines, do:

<?php
$Result
= str_replace( "\n", '<br />', $Text );
?>
up
6
fquffio at live dot it
4 months ago
Starting from PHP 4.3.10 and PHP 5.0.2, this should be the most correct way to replace <br /> and <br> tags with newlines and carriage returns.
<?php
/**
* Convert BR tags to newlines and carriage returns.
*
* @param string The string to convert
* @return string The converted string
*/
function br2nl ( $string )
{
    return
preg_replace('/\<br(\s*)?\/?\>/i', PHP_EOL, $string);
}
?>
(Please note this is a minor edit of this function: http://php.net/nl2br#86678 )

You might also want to be "platform specific", and therefore this function might be of some help:
<?php
/**
* Convert BR tags to newlines and carriage returns.
*
* @param string The string to convert
* @param string The string to use as line separator
* @return string The converted string
*/
function br2nl ( $string, $separator = PHP_EOL )
{
   
$separator = in_array($separator, array("\n", "\r", "\r\n", "\n\r", chr(30), chr(155), PHP_EOL)) ? $separator : PHP_EOL// Checks if provided $separator is valid.
   
return preg_replace('/\<br(\s*)?\/?\>/i', $separator, $string);
}
?>
up
6
Anders Norrbring
8 years ago
Seeing all these suggestions on a br2nl function, I can also see that neither would work with a sloppy written html line break.. Users can't be trusted to write good code, we know that, and mixing case isn't too uncommon.

I think this little snippet would do most tricks, both XHTML style and HTML, even mixed case like <Br> <bR /> and even <br            > or <br     />.

<?php
function br2nl($text)
{
    return 
preg_replace('/<br\\s*?\/??>/i', '', $text);
}
?>
up
7
ngkongs at gmail dot com
7 years ago
to replace all linebreaks to <br />
the best solution (IMO) is:

<?php
function nl2br2($string) {
$string = str_replace(array("\r\n", "\r", "\n"), "<br />", $string);
return
$string;
}
?>

because each OS have different ASCII chars for linebreak:
windows = \r\n
unix = \n
mac = \r

works perfect for me
up
2
blacknine313 at gmail dot com
6 years ago
After a recent post at the forums on Dev Shed, I noticed that it isn't mentioned, so I will mention it.

nl2br returns pure HTML, so it should be after PHP anti-HTML functions ( such as strip_tags and htmlspecialchars ).
up
0
Suleman Chikhalia
3 days ago
Looking for the reverse of the nl2br function? Here is a more succinct way to convert HTML line breaks to newlines (making a slight improvement to http://php.net/nl2br#86678):

<?php
/**
* Convert HTML line breaks to newlines
*
* @param string The string to convert
* @return string The converted string
*/
function br2nl($string)
{
    return
preg_replace('/<br\s*\/?>/i', "\n", $string);
}
?>
up
-1
darenschwenke at yahoo dot com
9 months ago
This one works with br tags having attributes, in any case,
closed or  not closed, and does not double linefeeds

<?php
/**
* convert br tags to nl
*
* @param string The string to convert
* @return string The converted string
*/

function br2nl($string)
{
    return
preg_replace("/<br[^>]*>\s*\r*\n*/is", "\n", $string);
}
?>

I combine this with strip_tags() for dead simple "contenteditable" fields allowing only text and linefeeds.
up
-2
j dot mons54 at gmail dot com
2 years ago
for bbcode :

<?php
$message
nl2br(preg_replace('#(\\]{1})(\\s?)\\n#Usi', ']', stripslashes($message)));
?>
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-10
hyponiq at gmail dot com
7 years ago
On the contrary, <b>mark at dreamjunky.comno-spam</b>, this function is rightfully named.  Allow me to explain.  Although it does re-add the line break, it does so in an attempt to stay standards-compliant with the W3C recommendations for code format.

According to said recommendations, a new line character must follow a line break tag.  In this situation, the new line is not removed, but a break tag is added for proper browser display where a paragraph isn't necessary or wanted.
up
-79
billhicks at yahoo dot com
7 months ago
Your new site does not work in ie.

But you already know this and I guess you don't really care.

its all about style now - funny because this is a php site not a css/java/ajax site.

piss off!!!!!!!!!!!!!!!
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