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Groups > comp.lang.c > #150930
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Protable way of reading str[4] as uint32_t |
| Date | 2020-03-31 10:59 -0700 |
| Organization | None to speak of |
| Message-ID | <871rp8v21d.fsf@nosuchdomain.example.com> (permalink) |
| References | <40d1f926-8737-4332-93f2-c37c46f731f9@googlegroups.com> <yOvgG.106450$Gy2.9178@fx30.iad> <875zeluvnz.fsf@nosuchdomain.example.com> <98d5d7c7-8d0f-40e8-b2bf-bdac3d1ac846@googlegroups.com> |
wyniijj@gmail.com writes:
> Keith Thompson於 2020年3月31日星期二 UTC+8上午10時04分43秒寫道：
[...]
>> And definitely use unsigned char rather than char, and test with values
>> exceeding 0x7f.
[...]
> Yes, the type str should be uint8_t. Should I write it
>
> union {
> uint8_t str[4];
> uint32_t value;
> } a;
>
> a.str[0]='\x12';
> a.str[1]='\x34';
> a.str[2]='\x56';
> a.str[3]='\x78';
>
> uint32_t b=(uint32_t)a.str[0] | ((uint32_t)a.str[1]<<8) | ((uint32_t)a.str[2] << 16) | ((uint32_t)a.str[3] << 24);
>
> a.value is useless.
No.
You've said elsewhere that the str array contains a UTF-8
encoding of a character (something you didn't initially mention).
The code above would be a way of interpreting the byte sequence
{ 0x12, 0x34, 0x56, 0x78 } as the integer value 0x12345678 --
but the way UTF-8 characters are encoded is very different from that.
https://en.wikipedia.org/wiki/UTF-8
--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips Healthcare
void Void(void) { Void(); } /* The recursive call of the void */
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Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-30 11:42 -0700
Re: Protable way of reading str[4] as uint32_t Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-03-30 20:14 +0100
Re: Protable way of reading str[4] as uint32_t Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-03-30 20:11 +0000
Re: Protable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-03-30 20:04 -0400
Re: Protable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-30 19:04 -0700
Re: Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-30 23:30 -0700
Re: Protable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-31 10:59 -0700
Re: Protable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-03-31 12:19 -0700
Re: Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-04-01 06:37 -0700
Re: Protable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-30 23:28 -0700
Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-03-31 11:29 +0000
Re: Portable way of reading str[4] as uint32_t wyniijj@gmail.com - 2020-03-31 09:59 -0700
Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-03-31 18:03 +0000
Re: Portable way of reading str[4] as uint32_t Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-02 19:09 -0700
Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-04-03 05:02 +0000
Re: Portable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 01:10 -0400
Re: Portable way of reading str[4] as uint32_t gazelle@shell.xmission.com (Kenny McCormack) - 2020-04-03 08:18 +0000
Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-04-03 09:48 +0000
Re: Portable way of reading str[4] as uint32_t gazelle@shell.xmission.com (Kenny McCormack) - 2020-04-03 11:07 +0000
Re: Portable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-03 09:41 -0500
Re: Portable way of reading str[4] as uint32_t Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-03 07:51 -0700
Re: Portable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-04-03 12:09 -0400
Re: Portable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-03 13:19 -0500
Re: Portable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 14:52 -0400
Re: Portable way of reading str[4] as uint32_t Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-03 12:10 -0700
Re: Portable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-03 15:17 -0500
Re: Portable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-03 23:39 -0400
Re: Portable way of reading str[4] as uint32_t Spiros Bousbouras <spibou@gmail.com> - 2020-04-03 21:28 +0000
Re: Portable way of reading str[4] as uint32_t Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-04-04 19:28 -0700
Re: Protable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-03-31 08:05 -0400
Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-03-31 09:12 -0500
Re: Protable way of reading str[4] as uint32_t Philipp Klaus Krause <pkk@spth.de> - 2020-03-31 17:27 +0200
Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-03-31 18:26 -0500
Re: Protable way of reading str[4] as uint32_t Jorgen Grahn <grahn+nntp@snipabacken.se> - 2020-04-01 06:03 +0000
Re: Protable way of reading str[4] as uint32_t Richard Damon <Richard@Damon-Family.org> - 2020-04-01 08:17 -0400
Re: Protable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-01 09:57 -0400
Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-01 09:47 -0500
Re: Protable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-01 11:48 -0400
Re: Protable way of reading str[4] as uint32_t BGB <cr88192@gmail.com> - 2020-04-01 12:37 -0500
Re: Protable way of reading str[4] as uint32_t James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-03-31 12:56 -0400
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