Hướng dẫn php replace n

(PHP 4, PHP 5, PHP 7, PHP 8)

nl2br — Inserts HTML line breaks before all newlines in a string

Description

nl2br(string $string, bool $use_xhtml = true): string

Parameters

The input string.

Whether to use XHTML compatible line breaks or not.

Return Values

Returns the altered string.

Examples

Example #1 Using nl2br()

echo nl2br("foo isn't\n bar");
?>

The above example will output:

Example #2 Generating valid HTML markup using the use_xhtml parameter

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

The above example will output:

Welcome

This is my HTML document

Example #3 Various newline separators

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

The above example will output:

This

is

a

string

See Also

• htmlspecialchars() - Convert special characters to HTML entities
• htmlentities() - Convert all applicable characters to HTML entities
• wordwrap() - Wraps a string to a given number of characters
• str_replace() - Replace all occurrences of the search string with the replacement string

CGameProgrammer at gmail dot com ¶

17 years ago

It's important to remember that this function does NOT replace newlines with
tags. Rather, it inserts a
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:

$Result = str_replace( "\n", '
', $Text );
?>

ngkongs at gmail dot com ¶

15 years ago

to replace all linebreaks to

the best solution (IMO) is:

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

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

works perfect for me

N/A ¶

13 years ago

Here's a more simple one:

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

Enjoy

fquffio at live dot it ¶

8 years ago

Starting from PHP 4.3.10 and PHP 5.0.2, this should be the most correct way to replace
and
tags with newlines and carriage returns.
/**
* 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('/\/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:
/**
* 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('/\/i', $separator, $string);
}
?>

aabaev ¶

3 years ago

double quotes !== single quotes

php > echo nl2br('\r\n');
\r\n
php > echo nl2br("\r\n");



Anders Norrbring ¶

16 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

and even or .

function br2nl($text)
{
    return  preg_replace('//i', '', $text);
}
?>

gautier dot michelin at gmail dot com ¶

2 years ago

This is a simple trick to transform newlines to paragraph a $string :

$string_with_paragraphs = "

".implode("

", explode("\n", $string))."

.

You can bring it to a function :

function nl2p($string) {
    return $string_with_paragraphs = "

".implode("

", explode("\n", $string))."

Collette ¶

2 years ago

Let's say a form text field does contain:
test line number 1
test line number 2

To remove all the line breaks and split the input into an array:

$input_from_text_field = preg_replace('#[\r\n]#','',nl2br($input_from_text_field,false));
$lines = explode("
",$input_from_text_field);

$lines will now be an array where $lines[0] = "test line number 1" and so on.

buzanits at gmail dot com ¶

4 years ago

If you write code that is to run in browser AND on the shell, this function could be useful. It uses PHP_EOL or
depending on the platform it runs:

function nl($string) {
  if(isset($_SERVER['SHELL'])) return preg_replace('/\/i', PHP_EOL, $string);
  return nl2br($string);
}

print

leo dot mauro dot desenv at gmail dot com ¶

6 years ago

I test empirically this function nl2br and nl2br2 (create by ngkongs at gmail dot com).
Both work nice with different ASCII chars for linebreak, but the function nl2br2 is faster than nl2br.

nl2br2 ~ 0.0000309944153 s
nl2br  ~ 0.0011141300201 s

The function nl2br2:
function nl2br2($string) {
  $string = str_replace(array("\r\n", "\r", "\n"), "
", $string);
  return $string;
}
?>

Justinas M. ¶

6 years ago

This is example with "\R" regex token which matches any unicode newline character.
"u" flag treate strings as UTF-16. Which is optional, depending on your use case.

public function nl2br($string)
{
  return preg_replace('/\R/u', '
', $string);
}?>

NOTE:
preg_replace versions are much slower than using str_replace version or built-in nl2br.
Check out pcre.backtrack_limit php.ini setting for information about PCRE limit. It's good to know.

Some PHP7 benchmarks:
// nl2br()function nl2br_str($string) {
  return str_replace(["\r\n", "\r", "\n"], '
', $string);
}

function

chad at nobodyfamous dot ca ¶

5 years ago

I just spent a whole day trying to figure out why my textarea $_POST was not getting
tags added by nl2br().  So for others

(INPUT_POST, 'text', FILTER_SANITIZE_SPECIAL_CHARS); ?> returns newlines as  and so nl2br will miss them.

rather use (INPUT_POST, 'text', FILTER_SANITIZE_STRING); ?> and newlines will remain intact so nl2br will pick them up.

blacknine313 at gmail dot com ¶

14 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 ).

darenschwenke at yahoo dot com ¶

8 years ago

This one works with br tags having attributes, in any case,
closed or  not closed, and does not double linefeeds

/**
* convert br tags to nl
*
* @param string The string to convert
* @return string The converted string
*/function br2nl($string)
{
    return preg_replace("/]*>\s*\r*\n*/is", "\n", $string);
}
?>

I combine this with strip_tags() for dead simple "contenteditable" fields allowing only text and linefeeds.

j dot mons54 at gmail dot com ¶

10 years ago

for bbcode :

$message =  nl2br(preg_replace('#(\\]{1})(\\s?)\\n#Usi', ']', stripslashes($message)));
?>

hyponiq at gmail dot com ¶

15 years ago

On the contrary, mark at dreamjunky.comno-spam, 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.