Numeric literals in other than base 10 - was Annoying octal notation

MRAB python at mrabarnett.plus.com
Mon Aug 24 00:15:55 CEST 2009


James Harris wrote:
> On 23 Aug, 00:16, Mel <mwil... at the-wire.com> wrote:
>> James Harris wrote:
>>> I have no idea why Ada which uses the # also apparently uses it to end
>>> a number
>>>   2#1011#, 8#7621#, 16#c26b#
>> Interesting.  They do it because of this example from
>> <http://archive.adaic.com/standards/83rat/html/ratl-02-01.html#2.1>:
> 
> Thanks for providing an explanation.
> 
>> 2#1#E8                    -- an integer literal of value 256
>>
>> where the E prefixes a power-of-2 exponent, and can't be taken as a digit of
>> the radix.  That is to say
>>
>> 16#1#E2
>>
>> would also equal 256, since it's 1*16**2 .
> 
> Here's another suggested number literal format. First, keep the
> familar 0x and 0b of C and others and to add 0t for octal. (T is the
> third letter of octal as X is the third letter of hex.) The numbers
> above would be
> 
>   0b1011, 0t7621, 0xc26b
> 
> Second, allow an arbitrary number base by putting base and number in
> quotes after a zero as in
> 
>   0"2:1011", 0"8:7621", 0"16:c26b"
> 
Why not just put the base first, followed by the value in quotes:

     2"1011", 8"7621", 16"c26b"

> This would work for arbitrary bases and allows an exponent to be
> tagged on the end. It only depends on zero followed by a quote mark
> not being used elsewhere. Finally, although it uses a colon it doesn't
> take it away from being used elsewhere in the language.
> 
> Another option:
> 
>   0.(2:1011), 0.(8:7621), 0.(16:c26b)
> 
> where the three characters "0.(" begin the sequence.
> 
> Comments? Improvements?
> 



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