blocks|key|1138745|text|ints过去是16位的(pdp11等)。转到32位架构是很困难的。人们正在变得越来越好:几乎没有人认为指针会在很长一段时间内适合(你不是吗？)或者文件偏移量，或者时间戳，或者...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1138746|8位字符已经有点不合时宜了。我们已经需要32位来保存世界上所有的字符集。|1138747|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

ints used to be 16 bits (pdp11, etc.). Going to 32 bit architectures was hard. People are getting better: Hardly anyone assumes a pointer will fit in a long any more (you don't right?). Or file offsets, or timestamps, or ...

8 bit characters are already somewhat of an anachronism. We already need 32 bits to hold all the world's character sets.

blocks|key|1353959|text|看起来你仍然可以在仓库中使用buy+an+IM6100+(即芯片上的PDP-8+)。这是一个12位的架构。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1353960|entityMap|0|LINK|mutability|MUTABLE|url|http://www.datasheetdirect.com/part/IM6100.html^0|E|D|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

It appears that you can still <a href="http://www.datasheetdirect.com/part/IM6100.html" rel="noreferrer">buy an IM6100</a> (i.e. a PDP-8 on a chip) out of a warehouse. That's a 12-bit architecture.

blocks|key|1354016|text|在德州仪器的C54x+DSP上，char也是16位的，例如在OMAP2中出现的DSP。还有其他具有16位和32位char的DSP。我想我甚至听说过24位DSP，但我不记得是什么了，所以可能是我想象出来的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1354017|另一个考虑因素是POSIX强制使用CHAR_BIT+==+8。因此，如果您正在使用POSIX，您可以假定它。如果后来有人需要将您的代码移植到POSIX的近似实现中，恰好有您使用的函数，但char的大小不同，这是他们的厄运。|1354018|不过，总的来说，我认为解决这个问题几乎总是比思考它更容易。只需输入CHAR_BIT即可。如果您想要精确的8位类型，请使用int8_t。你的代码将在没有提供实现的情况下编译失败，而不是静默地使用你不想要的大小。至少，如果我遇到了一个我有充分理由假设它的案例，那么我会断言它。|1354019|entityMap^0|G|4|1K|4|0|H|D|2L|4|0|X|8|1O|6|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|K|$]]

<code>char</code> is also 16 bit on the Texas Instruments C54x DSPs, which turned up for example in OMAP2. There are other DSPs out there with 16 and 32 bit <code>char</code>. I think I even heard about a 24-bit DSP, but I can't remember what, so maybe I imagined it.

Another consideration is that POSIX mandates <code>CHAR_BIT == 8</code>. So if you're using POSIX you can assume it. If someone later needs to port your code to a near-implementation of POSIX, that just so happens to have the functions you use but a different size <code>char</code>, that's their bad luck.

In general, though, I think it's almost always easier to work around the issue than to think about it. Just type <code>CHAR_BIT</code>. If you want an exact 8 bit type, use <code>int8_t</code>. Your code will noisily fail to compile on implementations which don't provide one, instead of silently using a size you didn't expect. At the very least, if I hit a case where I had a good reason to assume it, then I'd assert it.

blocks|key|1138910|text|许多数字信号处理器芯片都有16位或32位char。TI例行公事地制造这样的芯片for+example。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1138911|entityMap|0|LINK|mutability|MUTABLE|url|http://lists.xiph.org/pipermail/speex-dev/2006-April/004379.html^0|K|4|13|B|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

Many DSP chips have 16- or 32-bit <code>char</code>. TI routinely makes such chips <a href="http://lists.xiph.org/pipermail/speex-dev/2006-April/004379.html" rel="noreferrer">for example</a>.

blocks|key|1354162|text|DEC+PDP-8系列有一个12位字，尽管你通常使用8位ASCII作为输出(主要是在电传打字机上)。但是，还有一个6位字符代码，允许您在一个12位字中编码2个字符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1354163|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The DEC PDP-8 family had a 12 bit word although you usually used 8 bit ASCII for output (on a Teletype mostly). However, there was also a 6-BIT character code that allowed you to encode 2 chars in a single 12-bit word.

Every now and then, someone on SO points out that <a href="https://stackoverflow.com/questions/437470/type-to-use-to-represent-a-byte-in-ansi-c89-90-c/437640#437640"><code>char</code> (aka 'byte') isn't necessarily 8 bits</a>.

It seems that 8-bit <code>char</code> is almost universal. I would have thought that for mainstream platforms, it is necessary to have an 8-bit <code>char</code> to ensure its viability in the marketplace.

Both now and historically, what platforms use a <code>char</code> that is not 8 bits, and why would they differ from the "normal" 8 bits?

When writing code, and thinking about cross-platform support (e.g. for general-use libraries), what sort of consideration is it worth giving to platforms with non-8-bit <code>char</code>?

In the past I've come across some Analog Devices DSPs for which <code>char</code> is 16 bits. DSPs are a bit of a niche architecture I suppose. (Then again, at the time hand-coded assembler easily beat what the available C compilers could do, so I didn't really get much experience with C on that platform.)

What platforms have something other than 8-bit char?

编译器

每隔一段时间，就会有人在网上指出。看起来8位char几乎是通用的。我认为对于主流平台，有必要有一个8位的char，以确保它在市场上的生存能力。无论是现在还是历史上，哪些平台都使用非8位的char，为什么它们会与“正常”的8位不同？在编写代码并考虑跨平台支持(例如，对于通用库)时，对于使用非8位char的平台，值得考虑哪...

问除了8位字符之外，还有哪些平台可以使用其他字符？
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问除了8位字符之外，还有哪些平台可以使用其他字符？
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