Question

Given a literal string such as:

Hello\n\n\n\n\n\n\n\n\n\n\n\nWorld

I would like to reduce the repeated \n‘s to a single \n.

I’m using PHP, and been playing around with a bunch of different regex patterns. So here’s a simple example of the code:

$testRegex = '/(\\n){2,}/';
$test = 'Hello\n\n\n\n\n\n\n\n\nWorld';
$test2 = preg_replace($testRegex ,'\n',$test); 
echo "<hr/>test regex<hr/>".$test2;

I’m new to PHP, not that new to regex, but it seems ‘\n’ conforms to special rules. I’m still trying to nail those down.

Edit: I’ve placed the literal code I have in my php file here, if I do str_replace() I can get good things to happen, but that’s not a complete solution obviously.

Answer 1

To match a literal \n with regex, your string literal needs four backslashes to produce a string with two backlashes that’s interpreted by the regex engine as an escape for one backslash.

$testRegex = '/(\\\\n){2,}/';
$test = 'Hello\n\n\n\n\n\n\n\n\n\n\n\nWorld';
$test2 = preg_replace($testRegex, '\n', $test);