preg_replace removes multiple “\n”s

问题

How do I remove multiple occurrences of \n from the sample below and replace with just one occurrence of \n?

Basically I just want to remove multiple line breaks and replace them with just one line break.

\n\n\n\n\n\n\n\n \n\n \n\n\n\n\n\n\n    \n\n     \n\n     \n\n    \n\n    \n\n     \n\n     \n\n     \n     \n     \n     \n     \n     \n     \n\n     \n\n     \n\n     \nEDITION:  U.S.\n\n \nINTERNATIONAL\n\n     \nMÉXICO\n\n     \n\n     \nSet edition preference\n\n     \n\n     \n\n     \n\n     \nSign up\n\n     \nLog in\n\n     \n\n \n\n     \n\n     \n\n     \n\n\n\n\n\n\n\n\n\n\n\n     \n\n     \n\n\n \n\n \n\n     \n\n     \n\n    \n\n    \n\n     \n\n     \nHome\n\n     \nVideo\n\n     \nNewsPulse\n\n \nU.S.\n\n     \nWorld\n\n     \nPolitics\n\n     \nJustice\n\n     \nEntertainment\n\n     \nTech\n\n     \nHealth\n\n     \nLiving\n\n     \nTravel\n\n \nOpinion\n\n     \niReport\n\n     \nMoney\n\n     \nSports\n\n     \n\n    \n\n\n\n\n\n \n\n\n\n\n\n\n\n \n\n\n\n \n\n\n\n\n\n\n \n\nupdated 10:02 a.m.EDT, Fri June 3, 2011\n\n\n\n\n\n \n\n\n\n\n\nDr. Jack Kevorkian dead at 83\n\n\n\n\n\n\nThe Michigan pathologist who put assisted suicide on the world\'s medical ethics stage, apparently died of a blood clot, according to his attorney. FULL STORY

回答1:

Two ways

while(strpos($string, "\n\n") !== false)
  str_replace("\n\n", "\n", $string);

And

preg_replace("/\n+/", "\n", $string);

回答2:

This should work:

<?php
$string = "\n\n\n\n Text \n\n Text \n\n\n\n\n Text \n\n\n";

echo preg_replace("#[\n]+#", "\n", $string);

回答3:

If this is a real carriage return you can do this to remove successive carriage returns:

preg_replace('/\n+/', '\n', $yourString);

Else for the string '\n' you can do:

preg_replace('/(\\n)+/', '\n', $yourString);

Finally, if you want to remove all spaces in between your \n too you can do"

preg_replace('/\s*\n+/', '\n', $yourString);

回答4:

Try forcing the + match to be greedy, by using ++ instead.

preg_replace('/\n++/', "\n", $yourString);

回答5:

Strange, none of the code works? Example:

$barcodes = "5312353123123



5312353123123



5312353123123";
echo(     var_dump(   $barcodes     )     . '</br>' . "\n"  );
$barcodes = preg_replace('/\n+/', "\n", $barcodes);
exit(  var_dump(   $barcodes     )     . '</br>' . "\n"  );

Output:

string(55) "5312353123123 5312353123123 5312353123123"
string(55) "5312353123123 5312353123123 5312353123123"

That means the function does... nothing?

回答6:

Another way from the gotcha's examples on the man page for str_replace() is:

// Order of replacement
$str     = "Line 1\nLine 2\rLine 3\r\nLine 4\n";
$order   = array("\r\n", "\n", "\r");
$replace = '<br />';

// Processes \r\n's first so they aren't converted twice.
$newstr = str_replace($order, $replace, $str);

回答7:

Try:

$newstr = preg_replace("/\r\n\r\n|\r\r|\n\n/", "..", $str);

来源：https://stackoverflow.com/questions/6228367/preg-replace-removes-multiple-ns

标签

php

preg-replace

line-endings