Provide several php methods to replace newline characters

?$str="this is a test n";
$patten = array("rn", "n", "r");
?//Replace rn first, Then if n exists, finally replace r
$str=str_replace($order, "", $str);
?>

 //php has three ways to solve it
//1. Use str_replace to replace newlines
$str = str_replace(array("rn", "r", "n"), "", $str);
//2. Use regular replacement
$str = preg_replace('//s*/', '', $str);
//3. Use php Defined variables (recommended to use)
$str = str_replace(PHP_EOL, '', $str);

/*
 * Get the newline character of the user's operating system, n
* @access public
* @return string
*/
function get_crlf()
{
if (stristr($_SERVER['HTTP_USER_AGENT'], 'Win'))
{
$the_crlf = 'rn';
}
elseif (stristr($_SERVER['HTTP_USER_AGENT'], 'Mac'))
{
$the_crlf = 'r'; // for old MAC OS
}
else
{
$the_crlf = 'n';//The weight is bigger
}
return $the_crlf;
}

Note: When the front page is displayed, use nl2br to change the line break to

The second example:

I found an interesting thing:

$text="aaaa
ccc";
$text=str_replace('n',"",$text);
$text= str_replace('r',"",$text);
$text=str_replace('rn',"",$text);

Normally, the above The code should replace newlines, but it doesn't. Very frustrated, tried many times, but it just doesn't work. Finally changed it to this:

$text=str_replace("n","",$text);
$text=str_replace("r","",$text);
$text=str_replace("rn"," ",$text);

and it works. It turns out to be a problem with double quotes and single quotes!

Double quotation marks are less efficient than single quotation marks, because during the process of parsing double quotation marks by PHP, it will also judge whether there are variables inside, but single quotation marks will not make this judgment, so generally speaking, variables are not involved. I always use single quotes, but I didn’t expect that replacing the newline character this time would not work using single quotes...

Finally written as:

$order = array("rn", "n", "r");
$replace = '';
$text=str_replace($order, $replace, $text);

so you can replace the newlines. Isn't it very convenient?

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