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@REPLYADDR Janis Papanagnou
<janis_papanagnou+ng@hotmail.com>
@REPLYTO 2:5075/128 Janis Papanagnou
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It gets even more interesting...
$ typeset -li x=9223372036854775807 ; echo $((x))
9223372036854775807
$ typeset -li x=9223372036854775808 ; echo $((x))
-9223372036854775808
$ typeset -li x=10#9223372036854775807 ; echo $((x))
9223372036854775807
$ typeset -li x=10#9223372036854775808 ; echo $((x))
ksh: typeset: 10#9223372036854775808: arithmetic syntax error
$ typeset -li x=$(getconf ULONG_MAX) ; echo $((x))
-9223372036854775808
$ typeset -li x=10#$(getconf ULONG_MAX) ; echo $((x))
ksh: typeset: 10#18446744073709551615: arithmetic syntax error
...you can trigger an error message (which is good!) by explicitly
specifying the numeric base `10#` with the number.
On 10.09.2023 16:00, Janis Papanagnou wrote:
> It seems the below observed output is the result of a _float based_
> long-int math. Ksh`s man page says in chapter Arithmetic Evaluation:
> "Evaluations are performed using double precision floating point
> arithmetic or long double precision floating point for systems
> that provide this data type."
> Results seem thus be system dependent and (on my system) [unsigned]
> long integer calculations should not be done with values greater than
> 9223372036854775807 (if not less than that; I haven`t yet confirmed
> the reliability), and 64 bit certainly aren`t supported.
>
> typeset UINT_MAX ULONG_MAX (expected)
> 4294967295 18446744073709551615
>
> -i -1 0
> -ui 4294967295 0
> -li 4294967295 -9223372036854775808 (-1)
> -lui 4294967295 9223372036854775808 (18446744073709551615
> or 9223372036854775807)
>
>
> On 08.09.2023 16:20, Janis Papanagnou wrote:
>> On 08.09.2023 15:50, Janis Papanagnou wrote:
>>> Usually it is sufficient for me to work in Kornshell with integers
>>> (typeset -i) that support 32 bit (signed) data.
>>>
>>> Now playing with long integers (typeset -li) and 64 bit data I got
>>> puzzled about the results... (the two lines marked with "???")
>>>
>>> typeset -i x=$(getconf UINT_MAX) # -1 fff..ff
>>> typeset -i x=$(getconf ULONG_MAX) # 0 doesn`t fit
>>> typeset -li x=$(getconf UINT_MAX) # 4294967295 positive in `-li`
>>> typeset -li x=$(getconf ULONG_MAX) # -9223372036854775808 ???
>>> typeset -li16 x=$(getconf ULONG_MAX) # 16#8000000000000000 ???
>>> getconf ULONG_MAX # 18446744073709551615 fff..ff
>>> typeset -li x=16#ffffffffffffffff # -1
>>
>> Using unsigned types may shed some light on the issue...
>>
>> $ typeset -lui x=$(getconf ULONG_MAX) ; echo $x
>> 9223372036854775808
>>
>> ...not that this result wouldn`t open more/other questions.
>>
>>>
>>> What conversion/truncation/whatever happens when assigning a
>>> ULONG_MAX (which is an all `1`s number) to a long int [signed]
>>> type (where only the highest bit gets set, that obviously defines
>>> the minimum signed value)?
>>>
>>> Note that for `typeset -i` and UINT_MAX it is an all `1`s binary
>>> number, the decimal -1. And `typeset -li` is capable of carrying
>>> 64 `1` bits.
>>>
>>> (BTW; there`s no overflow error indication reported or a RC>0.)
>>>
>>> Janis
>>>
>>
>
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