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Groups > comp.lang.c++ > #82752
| From | Bonita Montero <Bonita.Montero@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: Can anyone improve this ? |
| Date | 2022-01-11 19:36 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <srkinu$qq7$1@dont-email.me> (permalink) |
| References | <srjdtm$d9c$1@dont-email.me> <srjjt8$khb$1@gioia.aioe.org> <srkeor$u3h$1@dont-email.me> <srkfgp$34v$1@dont-email.me> |
Am 11.01.2022 um 18:41 schrieb Christian Gollwitzer:
> Am 11.01.22 um 18:28 schrieb Bonita Montero:
>> Am 11.01.2022 um 10:50 schrieb Juha Nieminen:
>>> How does it compare to the more straightforward:
>>>
>>> std::size_t utf8Strlen(const char *str)
>>> {
>>> std::size_t length = 0;
>>> for(std::size_t index = 0; str[index]; ++index, ++length)
>>> if((str[index] & 0xC0) == 0xC0)
>>> while((str[index+1] & 0xC0) == 0x80)
>>> ++index;
>>> return length;
>>> }
>>
>> The issue with that solution is that it doesn't correctly detect
>> any kind of mis-formatted UTF-8-string. I get the number of chars
>> preceding a header-char from the table and check if there are an
>> according number of 0x80-headered chars.
>>
>
> I wrote this code once to check, if a string is valid UTF-8 - actually,
> I used this platform to test-drive it:
> https://leetcode.com/problems/utf-8-validation/ and it came off as the
> fastest solution handed in so far:
>
> ==================================================================
> enum utf8token { utf8lowbyte = 1, utf8doublet = 2, utf8triplet = 3,
> utf8quadruplet = 4, utf8highbyte, utf8fail };
>
> static utf8token utf8classify(unsigned char data) {
> if ((data & 0x80) == 0) { return utf8lowbyte; }
> if ((data & 0xC0) == 0x80) { return utf8highbyte;}
> if ((data & 0xE0) == 0xC0) { return utf8doublet; }
> if ((data & 0xF0) == 0xE0) { return utf8triplet; }
> if ((data & 0xF8) == 0xF0) { return utf8quadruplet; }
> return utf8fail;
> }
Sorry, that makes a lot of unprecitible branches.
That's while I used a table.
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Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-11 09:08 +0100
Re: Can anyone improve this ? Juha Nieminen <nospam@thanks.invalid> - 2022-01-11 09:50 +0000
Re: Can anyone improve this ? Juha Nieminen <nospam@thanks.invalid> - 2022-01-11 11:07 +0000
Re: Can anyone improve this ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-11 11:08 +0000
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-11 18:28 +0100
Re: Can anyone improve this ? Christian Gollwitzer <auriocus@gmx.de> - 2022-01-11 18:41 +0100
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-11 19:36 +0100
Re: Can anyone improve this ? Öö Tiib <ootiib@hot.ee> - 2022-01-11 21:54 -0800
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-11 21:51 +0100
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-12 14:19 +0100
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-12 14:20 +0100
Re: Can anyone improve this ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-12 14:14 +0000
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-12 17:20 +0100
Re: Can anyone improve this ? "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-01-12 08:38 -0800
Re: Can anyone improve this ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-01-12 16:55 +0000
Re: Can anyone improve this ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-16 12:09 -0800
Re: Can anyone improve this ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-16 12:12 -0800
Re: Can anyone improve this ? Öö Tiib <ootiib@hot.ee> - 2022-01-16 13:00 -0800
Re: Can anyone improve this ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-17 10:13 -0800
Re: Can anyone improve this ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-17 10:28 -0800
Re: Can anyone improve this ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-01-17 21:51 +0100
Re: Can anyone improve this ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-17 16:16 -0800
Re: Can anyone improve this ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-01-17 22:43 -0800
Re: Can anyone improve this ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-01-18 12:09 +0100
Re: Can anyone improve this ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-18 09:18 +0100
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