Re: [PHP] substr and UTF-8
On Wed, 30 Aug 2006 21:46:18 +0700
"Peter Lauri" <[EMAIL PROTECTED]> wrote:
> function is_utf8_start($b) {
> return (($b & 0x80) == 0) || ($b & 0x40);
> }
> [/snip]
>
> :) I think I will go with the mb_substr function, it works for me :)
Yeah, I guess that's the right thing to do. Otherwise, in a year you
won't remember what the cryptic masking is all about.
Mike
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RE: [PHP] substr and UTF-8
[snip]
Actually this is false. I don't know what I was thinking. The high bit
will be set in all bytes of a UTF-8 byte sequence. If it's not it's an
ASCII character.
The bytes are actually layed out as follows [1]:
U- ___ U-007F: 0xxx
U-0080 ___ U-07FF: 110x 10xx
U-0800 ___ U-: 1110 10xx 10xx
U-0001 ___ U-001F: 0xxx 10xx 10xx 10xx
So there's no way to tell the last byte of a UTF-8 byte sequence but you
can tell if it's the first byt looking at bits 7 and 8. Specifically,
if bit 8 is not on, the character is ASCII and thus the "start" of a
new character. Otherwise, if bit 7 is on it's the start of a new UTF-8
byte sequence.
function is_utf8_start($b) {
return (($b & 0x80) == 0) || ($b & 0x40);
}
[/snip]
:) I think I will go with the mb_substr function, it works for me :)
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Re: [PHP] substr and UTF-8
On Wed, 30 Aug 2006 10:08:36 -0400
Michael B Allen <[EMAIL PROTECTED]> wrote:
> On Wed, 30 Aug 2006 18:34:20 +0700
> "Peter Lauri" <[EMAIL PROTECTED]> wrote:
>
> > Hi group,
> >
> > I want to limit the number of characters that are shown in a script. The
> > characters happen to be Thai, and the page is encoded in UTF-8. Everything
> > works, except when I want to cut the text (just take start of string).
> >
> > I do:
> >
> > echo substr($thaistring, 0, 30);
> >
> > The beginning of the string works fine, but the last character does mostly
> > "break". How can I determine the start and end of a character.
>
> The last byte of a UTF-8 character does not have bit 8 set whereas all
> preceeding bytes do.
Actually this is false. I don't know what I was thinking. The high bit
will be set in all bytes of a UTF-8 byte sequence. If it's not it's an
ASCII character.
The bytes are actually layed out as follows [1]:
U- ___ U-007F: 0xxx
U-0080 ___ U-07FF: 110x 10xx
U-0800 ___ U-: 1110 10xx 10xx
U-0001 ___ U-001F: 0xxx 10xx 10xx 10xx
So there's no way to tell the last byte of a UTF-8 byte sequence but you
can tell if it's the first byt looking at bits 7 and 8. Specifically,
if bit 8 is not on, the character is ASCII and thus the "start" of a
new character. Otherwise, if bit 7 is on it's the start of a new UTF-8
byte sequence.
function is_utf8_start($b) {
return (($b & 0x80) == 0) || ($b & 0x40);
}
Mike
[1] http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
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http://www.ioplex.com/
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Re: [PHP] substr and UTF-8
On Wed, 30 Aug 2006 18:34:20 +0700 "Peter Lauri" <[EMAIL PROTECTED]> wrote: > Hi group, > > I want to limit the number of characters that are shown in a script. The > characters happen to be Thai, and the page is encoded in UTF-8. Everything > works, except when I want to cut the text (just take start of string). > > I do: > > echo substr($thaistring, 0, 30); > > The beginning of the string works fine, but the last character does mostly > "break". How can I determine the start and end of a character. The last byte of a UTF-8 character does not have bit 8 set whereas all preceeding bytes do. Mike -- Michael B Allen PHP Active Directory SSO http://www.ioplex.com/ -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] substr and UTF-8
Peter Lauri wrote: > Hi group, > > I want to limit the number of characters that are shown in a script. The > characters happen to be Thai, and the page is encoded in UTF-8. Everything > works, except when I want to cut the text (just take start of string). > > I do: > > echo substr($thaistring, 0, 30); > > The beginning of the string works fine, but the last character does mostly > "break". How can I determine the start and end of a character. become familiar with (and install) the mb_string extension > > I hope the problem is clear enough, is it? :) > > Best regards, > Peter Lauri > > www.lauri.se - personal web site > www.dwsasia.com - company web site > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] substr and UTF-8
Hi group, I want to limit the number of characters that are shown in a script. The characters happen to be Thai, and the page is encoded in UTF-8. Everything works, except when I want to cut the text (just take start of string). I do: echo substr($thaistring, 0, 30); The beginning of the string works fine, but the last character does mostly "break". How can I determine the start and end of a character. I hope the problem is clear enough, is it? :) Best regards, Peter Lauri www.lauri.se - personal web site www.dwsasia.com - company web site -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
