Regex - backslash cannot be escaped inside a character class, why?

Question

I've got a short and simple PHP script, in which I want to look for every series of two or more backslashes inside a string, and replace it with a single backslash:

<?php
    $link = 'www\\root\\\\test\\';
    echo preg_replace('/[\\]{2,}/', '\\', $link);
?>

So I guess that I actually escaped all the backslashes properly, but when I run the code, it gives me back an error that says that the terminating ] bracket could not be found. So it seems to me that this one is escaped instead of the backslash, which confuses me. Does escaping a backslash inside a character class actually take different methods than that?

You could just search for it in Google. Very [easy to find](http://stackoverflow.com/a/15369828/3832970). — Wiktor Stribiżew, Feb 29 '16 at 12:25
[Backslash PHP regex](https://www.google.pl/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=backslash%20php%20regex) => First result? — Wiktor Stribiżew, Feb 29 '16 at 12:27
I didn't link my search with PHP first since I didn't suspect the problem to be connected with that first... welp. — StrikeAgainst, Feb 29 '16 at 12:29

score 0 · Answer 1 · answered Feb 29 '16 at 12:24

0

Ah alright, so I came across an answer myself:

preg_replace('/[\\\\]{2,}/', '\\', $link);

I need to double escape it, since PHP needs to escape it by itself first.

answered Feb 29 '16 at 12:24

StrikeAgainst

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Regex - backslash cannot be escaped inside a character class, why?

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