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: Carl Hoefs <email@hidden>
- Date: Fri, 12 Sep 2014 19:11:22 -0700
| Okay, it looks like I had mis-remembered this. Apparently it’s long that changes its size, not int. I had it backward. I’ll use uint32_t and see how that fares. Thx! -Carl On Sep 12, 2014, at 7:05 PM, Carl Hoefs < email@hidden> wrote: 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 XData 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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