C++ U32 type header

Question

I want to use U32 type but I can't find the header where it is defined. Does anyone know?

score 15 · Accepted Answer · edited Feb 16 '23 at 12:42

15

There is no standard type called U32, but if you #include <cstdint> (stdint.h for C) you can use std::uint32_t¹, a 32 bit unsigned integer, which is (I assume) what you want.

Here is a list of types in the cstdint header:

namespace std {
    int8_t
    int16_t
    int32_t
    int64_t
    int_fast8_t
    int_fast16_t
    int_fast32_t
    int_fast64_t
    int_least8_t
    int_least16_t
    int_least32_t
    int_least64_t
    intmax_t
    intptr_t
    uint8_t
    uint16_t
    uint32_t
    uint64_t
    uint_fast8_t
    uint_fast16_t
    uint_fast32_t
    uint_fast64_t
    uint_least8_t
    uint_least16_t
    uint_least32_t
    uint_least64_t
    uintmax_t
    uintptr_t
}

¹ Thanks Martinho Fernandes for pointing out that these types are in the namespace std.

edited Feb 16 '23 at 12:42

anatolyg

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answered Aug 28 '11 at 00:21

Seth Carnegie

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On "Game Engine Architecture" there a code sppinet that uses U32... thats why I'm asking... – Tiago Costa Aug 28 '11 at 00:25
@Tiago: You realize that C has the `typedef` keyword that lets you make type aliases? – Kerrek SB Aug 28 '11 at 00:26
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Note that the types in `` are in namespace `std`. – R. Martinho Fernandes Aug 28 '11 at 01:19
I like style of u32/u64... , is there an off-shelf header file that defined these types ? many thank!!! – yushang Jan 15 '21 at 11:21

user46748 · Answer 2 · 2015-10-13T07:37:40.077

2

U32 is an idiomatic shortcut for an unsigned int. Its common definition is:

typedef unsigned int U32;

But the main reason for its use is to be able to control the actual definition manually. Hope this helps.

edited Oct 13 '15 at 07:37

answered Oct 13 '15 at 06:59

user46748

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`unsigned int` is not guaranteed to be 32 bits so such a typedef is just really bad. – ChrisWue Feb 09 '16 at 19:03
yup, throw a static_assert in there :) – paulm Aug 12 '16 at 16:27

score 2 · Answer 3 · answered Aug 28 '11 at 00:26

While cstdint might be a solution, it's not universal -- MSVC versions before 2010 didn't ship with that one. If writing for multiple platforms you'll need to supply the standard types yourself if MSVC < 2010 is detected. Or use the boost one if you use boost.

C++ U32 type header

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