This page is intended as a reference for functionality PHP provides which can either help with handling UTF-8 or should be regarded as a risk when used in conjunction with UTF-8 encoded strings. Further information can be found on the Internationalization (I18N) and Character Sets / Character Encoding Issues pages.

It talks about the "dangerous" functionality PHP has (issues that the language has in current functions) when using things like the PCRE extension, the string extension, the array methods, handling variables, the XML extensions (DOM and SAX), image manipulation, and URL parsing functionality.

So I've got this string (in PHP) and I need to scan through it character by character. I can't scan byte by byte because it's 2007, our users write in all sorts of languages, and the string is UTF-8.

To remedy the situation, he falls back on an old standby - the mb_* functions, mb_substr and mb_strlen. His benchmarks show that, with a 1500 character string, running his sample script gives him around 61 scans per second. (The PHP6 version with TextIterator works much faster, though - 450 scans per second).