mb_strpos vs strpos, what's the difference?

php utf-8 strpos
Federkun picture Federkun · Dec 17, 2012 · Viewed 10k times · Source

Yes: I know. We should use mb_* function when we're working with multibyte char. But when we're using strpos? Let's take a look this code (saved in utf-8)

var_dump(strpos("My symbol utf-8 is the €.", "\xE2\x82\xAC")); // int(23)

There is a difference of using mb_strpos? Does't makes this work the same jobs? After all, does't strpos seek a string (multiple byte)? Is there a reason to use instead strpos?

Answer

Esailija picture Esailija · Dec 17, 2012

For UTF-8, matching the byte sequence is exactly the same as matching character sequence.

So they both will find the needle at exactly the same point, but mb_strpos counts full UTF-8 byte sequencees before the needle, where as strpos calculates any bytes. So if your string had another multi-byte UTF-8 sequence, the results would be different:

strpos("My symbolö utf-8 is the €.", "€") !== mb_strpos("My symbolö utf-8 is the €.", "€", 0, "UTF-8")

But:

strpos("My symbol utf-8 is the €.", "€") === mb_strpos("My symbol utf-8 is the €.", "€", 0, "UTF-8")

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