How to remove multiple newlines (\n) from json string?

Question

It seems to be a problem with magic quotes. The original string just contains \n and \n\n and \n\n\n and \n\r and so on. These newlines arent interpreted by the browser.

What we wanna do is: to replace more than 2 newlines with just 1 single \n.

What we tried yet: a lot of different regular expressions with preg_replace, but the \n wont be kicked out.

Any ideas?

Heres an example (updated on your suggestions - but still not working):

echo '<h3>Source:</h3>';
$arr_test = array(
    'title'     => 'my title',
    'content'   => 'thats my content\n\n\n\nwith a newline'
);
$json_text = json_encode($arr_test);
$json_text = stripslashes($json_text);  //if I leave that out, then \\n will echo
echo $json_text;
// OUTPUT: {"title":"my title","content":"thats my content\n\n\n\nwith a newline"}

echo '<h3>Result 1:</h3>';
$pattern = '/\n{2,}/';
$result1 = preg_replace($pattern,"x",$json_text);
echo $result1;
// OUTPUT: {"title":"my title","content":"thats my content\n\n\n\nwith a newline"}

echo '<h3>Result 2:</h3>';
$result2 = preg_replace( '/([\n]+)/s', 'x', $json_text, -1, $count );
echo $count;
// OUTPUT: 0
echo $result2;
// OUTPUT: {"title":"my title","content":"thats my content\n\n\n\nwith a newline"}

I think the second regular expression you tried has a typo on the fourth character! (aka: please show some of your work and the results, so it is easy to see if it's just an error in the expression, or something different (strange stuff in the json)) — Nanne
– Nanne, Commented Apr 3, 2012 at 12:52
What have you tried? And did you include /s modifier which includes new lines? — Chris Gessler
– Chris Gessler, Commented Apr 3, 2012 at 12:57

Sascha Goerting · Accepted Answer · 2012-04-03 14:25:42Z

1

You could also try looping through the string and replace two newlines with one until no double newline is left:

echo '<h3>Result 4:</h3>';
$result4 = $json_text;
do{
    $result4 = str_replace('\n\n','\n',$result4, $count);
}while($count>0);

echo $result4;
// OUTPUT: {"title":"my title","content":"thats my content\nwith a newline"}

or with preg_replace:

echo '<h3>Result 5:</h3>';

$result5 = preg_replace('/(\\\n)+/m', '\\\n', $json_text);

echo $result5;
// OUTPUT: {"title":"my title","content":"thats my content\nwith a newline"}

edited Apr 3, 2012 at 14:25

answered Apr 3, 2012 at 14:18

Sascha Goerting

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Comments

safarov · Accepted Answer · 2012-04-03 14:18:13Z

1

if(get_magic_quotes_gpc()) {
   $string =  stripslashes($string); // $string sended with POST or GET 
}

$string = str_replace("\n\n", "\n", $string); // only for 2 newlines

OR

$string = preg_replace('/\n{2,}/s', '\n', $string); // more than 2 newlines

edited Apr 3, 2012 at 14:18

answered Apr 3, 2012 at 12:54

safarov

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3 Comments

Chris Gessler Over a year ago

If you replace 2 with 1, what happens when there are three? Three goes to two, so you would need to perform the replace twice.

safarov Over a year ago

@ChrisGessler second solution with preg_replace works for more than 2

Chris Gessler Over a year ago

without the /s modifier, how will go beyond one line?

web-nomad · Accepted Answer · 2012-04-03 12:58:02Z

0

try this:

// replace 2 or more consecutive newlines with a single newline
$string = preg_replace("/\n\n+/i", "\n", $string);

answered Apr 3, 2012 at 12:58

web-nomad

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Comments

Chris Gessler · Accepted Answer · 2012-04-03 13:06:16Z

0

Try this:

Replace all \n characters (1 or more) with \n
/s modifier - include multiple lines

>     $string = preg_replace( $'/([\n]+)/s', '\n', $string, -1, $count );                                               
>     echo $count;

answered Apr 3, 2012 at 13:06

Chris Gessler

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Comments

Ravi Jethva · Accepted Answer · 2012-04-03 13:25:25Z

0

echo str_replace("\n", "", "aassasa\n \n aasassf \n saaaaafs asaf ssaf \n afsf \n ");

just for your demo

echo str_replace("a","","aaabcefefgaaaaaaaaaaamnopqraaaaaa");

edited Apr 3, 2012 at 13:25

answered Apr 3, 2012 at 12:55

Ravi Jethva

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2 Comments

Chris Gessler Over a year ago

doesn't this simply replace all \n characters with empty string?

Chris Gessler Over a year ago

how does it leave just 1 \n when multiples are present? i.e. \n\n\n

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