Question

I come across a php regular expression, mentioned below, I am not sure why \q\ is used in it, can anybody help me to understand this?

$strBuildTitle="SOME URL";
$patterns[0] = "/[^a-zA-Z0-9\q\ ]/";        
$replacements[0] = " ";

$strBuildTitle = preg_replace($patterns, $replacements, $strBuildTitle);

I believe it tries to remove any non-alpha-numeric character from the given url, not sure why \q\ is used here. Is is related with removal of quotes?

Answer 1

\q and \ aren’t valid escape sequences.

In double quoted strings, it’s PHP’s policy to ignore those and replace them with their apparent value, meaning \ simply becoming and \q becoming q. The latter case already being covered by [a-z].