PHP string functions vs mbstring functions

Question

I have an application that has so far been in English only. Content encoding throughout templates and database has been UTF-8. I am now looking to internationalize/translate the application into languages that have character sets absolutely needing UTF-8.

The application uses various PHP string functions such as strlen(), strpos(), substr(), etc, and my understanding is that I should switch these for multi-byte string functions such as mb_strlen(), mb_strpos(), mb_substr(), etc, in order for multi-byte characters to be handled correctly. I've tried to read around this topic a little but virtually everything I can find goes deep into "encoding theory" and doesn't provide a simple answer to the question: If I'm using UTF-8 throughout, can I switch from using strlen() to mb_strlen() and expect things to work normally in for example both English and Arabic, or is there something else I still need to look out for?

Any insight would be welcome, and apologies if I'm offending someone who has encoding close to their heart with my relative ignorance.

Answer 1

No. Since bytearrays are also strings in PHP, a simple replacement of the 8-bit string functions with their mb_* counterparts will cause nothing but trouble. Functions like strlen() and substr() are probably more frequently used with bytes than actual text strings.

At the place I last worked, we managed to build a multilingual web-site (Arabic, Hindi, among other languages) in PHP without using the mbstring library at all. Text string manipulation actually doesn't happen that often. When it does, it would require far more care than just changing a function name. Most of the challenges, I've found, lie on the HTML side. Getting a page layout to work with a RTL language is the non-trivial part.

I don't know if you're just using Arabic as an example. The difficulty of internationalization can vary quite substantially depending on whether "international" means European languages only (plus Russian), or if it's inclusive of Middle-Eastern, South-Asian, and Far-East languages.

Answer 2

Check the status of the mbstring.func_overload flag in php.ini

If (ini_get('mbstring.func_overload') & 2) then functions like strlen() (as listed here) are already overloaded by the mb_strlen() function, so there is no need for you to call the mb_* functions explicitly.