Does c++11 have something like quint8?

Question

There are some types in Qt, for example quint8 that is guaranteed to be 8-bit on all platforms supported by Qt.

I am wondering if C++11 has such kind of type? if not, what is the alternative for this?

Thanks.

Can types defined in [stdint.h](http://www.cplusplus.com/reference/cstdint/) solve this problem? — Gluttton, Jun 11 '14 at 18:35
Yes it does check http://www.cplusplus.com/reference/cstdint/ — 101010, Jun 11 '14 at 18:35
@ColeJohnson: If searching for the question doesn't turn up anything, try searching for the obvious answer. I found http://stackoverflow.com/questions/20237451/fixed-length-data-types-in-c-c — MSalters, Jun 12 '14 at 09:19

score 14 · Accepted Answer · edited Jun 15 '14 at 23:58

14

Yes, C++11 adds types with more precisely defined sizes. Here's the reference.

They are defined in <cstdint>.

You are guaranteed to have these:

intmax_t        uintmax_t

int_least8_t    uint_least8_t
int_least16_t   uint_least16_t
int_least32_t   uint_least32_t
int_least64_t   uint_least64_t

int_fast8_t     uint_fast8_t
int_fast16_t    uint_fast16_t
int_fast32_t    uint_fast32_t
int_fast64_t    uint_fast64_t

You may or may not have these:

int8_t          uint8_t 
int16_t         uint16_t
int32_t         uint32_t
int64_t         uint64_t

intptr_t        uintptr_t

Explanations:

The u prefix means unsigned.
The least variants are the smallest integer types available with at least that width.
The fast variants are the fastest integer types available with at least that width.
The intptr variants are guaranteed to be convertible to void* and back.
The max variants are the largest available types.

edited Jun 15 '14 at 23:58

Cole Tobin

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answered Jun 11 '14 at 18:37

Lstor

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what does fast really mean? – camino Jun 11 '14 at 18:44
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@camino: "At least as fast as any other integer type with at least the specified width." – Lstor Jun 11 '14 at 18:45
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@camino That the type only guarantees a certain minimum length, but if on the given platform a longer type is "faster" to deal with, it will be used instead. – Kuba hasn't forgotten Monica Jun 11 '14 at 18:46
The `intprt` variants are not *compatible* with `void*`; type compatibility is a much stronger condition. The guarantee is that converting a `void*` value to `intptr_t` or `uintptr_t` and back to `void*` yields the original `void*` value (i.e., there's no loss of information). Both types are optional. – Keith Thompson Jun 11 '14 at 18:59
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From what I know, compilers aren't guaranteed to have those. They are only required to have `typedef`s of those form, not those specifically. Unless something has changed in the standard. – Cole Tobin Jun 11 '14 at 19:17
@ColeJohnson: That is correct, but do you think that matters for OP? – Lstor Jun 11 '14 at 19:18
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I'm saying your claim that "you are _guaranteed_ to have" (emphasis mine) is wrong. – Cole Tobin Jun 11 '14 at 19:19
@ColeJohnson: You are guaranteed to have a typename in `` with each of those names. I'm not saying that they are separate types, just that they are present and can be used. I don't think it's relevant whether it's a separate type or a `typedef`, but maybe I'm missing your point? – Lstor Jun 11 '14 at 19:21
What I personally do not understand in this answer is the brain dump of all the types instead of just focusing on the question of quint*8*. I think from the question's point of view, all the rest is red-herring and needless noise. Also, it is worth noting, as per my answer, that this will not work on all the platforms that Qt supports. – László Papp Jun 12 '14 at 07:48
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@FinalContest: I respectfully disagree, and read the quint*8*-part as an example rather than the complete list of what he needs. Besides, listing all types is more useful for future googlers. Since OP explicitly asks if C++11 adds support for such types, I presume that he is aware of the limitation and has support for C++11. – Lstor Jun 12 '14 at 08:40
The question was `Does c++11 have something like quint8?`. If someone asks about shared pointers, you do not start talking about the scoped, unique, auto, weak, borrowed and other pointers because the majority of that would be red-herring, and hence the signal/noise ratio is very low to get the useful information out. What people usually do on SO if they want to provide details is to give a link to the further details. How max or intptr is relevant to quint8 or even quint16/32/64, I do not know. (Btw, the OP is also saying "type similar to quint8' and "all platforms suppoted by Qt") – László Papp Jun 12 '14 at 08:58

László Papp · Answer 2 · 2014-06-11T18:43:10.063

Yes, it does, and even more. From the documentation:

uint8_t unsigned integer type with width of 8
uint_fast8_t fastest unsigned integer type with width of 8
uint_least8_t smallest unsigned integer type with width of at least 8

Disclaimer: this will not obviously work on platforms where Qt is supported and does not have C++11. If you plan to support those, stick with your quint8, otherwise go drop it in favor of modern C++.

Make sure you will have this in your qmake project file to actually enable C++11:

CONFIG += c++11

Does c++11 have something like quint8?

2 Answers2