Re: Implicit conversion loses integer precision in x86_64
Re: Implicit conversion loses integer precision in x86_64
- Subject: Re: Implicit conversion loses integer precision in x86_64
- From: Greg Weston <email@hidden>
- Date: Sat, 13 Sep 2014 07:36:12 -0400
uint32_t. That and its relatives were defined specifically for such needs.
> So what datatype do I specify to obtain an unsigned 4-byte integer, consistent across OS X and iOS platforms?
> -Carl
>
>> On Sep 12, 2014, at 6:26 PM, Roland King <email@hidden> wrote:
>>
>>
>>> On 13 Sep 2014, at 9:17 am, Carl Hoefs <email@hidden> wrote:
>>>
>>> OS X 10.9.4, Xcode 5.1.1
>>>
>>> For my OS X app, for both Project & Target I'm building with:
>>>
>>> Architectures "Standard Architectures (64-bit Intel) (x86_64)'.
>>> Build Active Architecture Only YES
>>> Supported Platforms OS X
>>> Valid Architectures x64_64
>>>
>>> However Xcode complains about the following:
>>>
>>> unsigned long myvalue = 16;
>>> unsigned int urvalue = myvalue; <—= WARNING
>>>
>>> "Implicit conversion loses integer precision: 'unsigned long' to 'uint32_t (aka 'unsigned int')"
>>>
>>> Aren't 'unsigned long' and 'unsigned int' identical 32-bit quantities in x86_64?
>>> -Carl
>>
>> No. From the admittedly rather old 64-bit transition guide. That fits with my mental model of what ‘long’ usually tends to mean.
>> Table 2-1 Size and alignment of base data types in OS X
>> Data type
>> ILP32 size
>> ILP32 alignment
>> LP64 size
>> LP64 alignment
>> char
>> 1 byte
>> 1 byte
>> 1 byte
>> 1 byte
>> short
>> 2 bytes
>> 2 bytes
>> 2 bytes
>> 2 bytes
>> int
>> 4 bytes
>> 4 bytes
>> 4 bytes
>> 4 bytes
>> long
>> 4 bytes
>> 4 bytes
>> 8 bytes
>> 8 bytes
>> pointer
>> 4 bytes
>> 4 bytes
>> 8 bytes
>> 8 bytes
>> size_t
>> 4 bytes
>> 4 bytes
>> 8 bytes
>> 8 bytes
>> long long
>> 8 bytes
>> 4 bytes
>> 8 bytes
>> 8 bytes
>> fpos_t
>> 8 bytes
>> 4 bytes
>> 8 bytes
>> 8 bytes
>> off_t
>> 8 bytes
>> 4 bytes
>> 8 bytes
>> 8 bytes
>
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