[fpc-pascal] Writing floating points to steams
Torsten Bonde Christiansen
tc at epidata.info
Wed Jan 13 10:45:51 CET 2016
On 2016-01-13 10:40, Mark Morgan Lloyd wrote:
> Torsten Bonde Christiansen wrote:
>> On 2016-01-13 10:06, Mark Morgan Lloyd wrote:
>>> Serguei TARASSOV wrote:
>>>> On 13/01/2016 08:47, fpc-pascal-request at lists.freepascal.org wrote:
>>>>> On 2016-01-12 10:45, Torsten Bonde Christiansen wrote:
>>>>>> Since TStream doesn't have any native WriteFloat/Double and the
>>>>>> some conversion is needed - but what is a good strategy for this?
>>>> Depends on size constraints.
>>>> In the simple case you should convert float to locale-independent
>>>> string value (no spaces, no commas separators) then write it.
>>>> If the size does matter, you may convert float to corresponding
>>>> byte array then write it.
>>> Can I ask a naive question here please: does a binary stream store
>>> endianness anywhere? In other words, is there any indication that
>>> something running on ARM is about to get into trouble by reading
>>> something written by (big-endian) MIPS?
>> Not that I'm aware of - i would think of it as a stream of bytes.
>> Endianess is defined by the CPU not by the file.
> Thanks, I assumed that was the case but thought it worth checking.
> I suppose that one could stream variants, i.e. the enumeration saying
> what one was followed by a value.
>>> Should writing binary floating point to a stream note that it's IEEE
>>> format, just in case anybody ever tries to process it on a platform
>>> that supports alternatives?
>> It would be great if storing floating point could be in IEEE, to have
>> a standard as reference.
> I'm not at all sure about this, but I think I've seen something that
> suggested that byte ordering in external representations was covered
> by the standard.
I'm not even sure how (or even if) TStream decendants handles endianness
for integers.... I'm guessing they are not.
More information about the fpc-pascal