Does preg_replace() change my character set?

问题

I have the following piece of code which seems to be changing my character set.

     $html = "à";
     echo $html;  // result: à
     $html = preg_replace("/\s/", "", $html);
     echo $html;  // result: ?

However, when I use [\t\n\r\f\v] as my pattern instead of the special character \s it works fine:

     $html = "à";
     echo $html;  // result: à
     $html = preg_replace("/[\t\n\r\f\v]/", "", $html);
     echo $html;  // result: à

Why is that?

回答1:

I have the same problem. It is because of UTF8.

à is 0xc3a0 in UTF8. In PHP you can write like this: "\xc3\xa0".

With PCRE the /s match 0xa0 like it was ASCII "Non-breaking space".

You can use the u flag to resolve the problem.

$html = preg_replace("/\s/u", "", $html);

来源：https://stackoverflow.com/questions/19629893/does-preg-replace-change-my-character-set