[snip]
Actually this is false. I don't know what I was thinking. The high bit
will be set in all bytes of a UTF-8 byte sequence. If it's not it's an
ASCII character.
The bytes are actually layed out as follows [1]:
U-00000000 U-0000007F: 0xxxxxxx
U-00000080 U-000007FF: 110xxxxx 10xxxxxx
U-00000800 U-0000FFFF: 1110xxxx 10xxxxxx 10xxxxxx
U-00010000 U-001FFFFF: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
So there's no way to tell the last byte of a UTF-8 byte sequence but you
can tell if it's the first byt looking at bits 7 and 8. Specifically,
if bit 8 is not on, the character is ASCII and thus the "start" of a
new character. , if bit 7 is on it's the start of a new UTF-8
byte sequence.
function is_utf8_start($b) {
return (($b & 0x80) == 0) || ($b & 0x40);
}
[/snip]
:) I think I will go with the mb_substr function, it works for me :)