问题
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?
回答1:
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")
回答2:
Depending on the character set in use and the string being searched for, this may or may not make a difference.
strpos() looks for the byte sequence that is passed as the needle.
mb_strpos() does the same thing but it also respects character boundaries.
So strpos() will match if the byte sequence occurs anywhere in the string. mb_strpos() will only match if the byte sequence also represents a valid set of complete characters.
来源：https://stackoverflow.com/questions/13913411/mb-strpos-vs-strpos-whats-the-difference