Functional schmunctional...

[Steve Holden]

Terry Reedy wrote:
> r0g wrote:
> 
>>
>> def inet2ip(n):
>>   p = (n/16777216)
>>   q = ((n-(p*16777216))/65536)
>>   r = ((n-((p*16777216)+(q*65536)))/256)
>>   s = ((n-((p*16777216)+(q*65536)+(r*256))))
>>   return str(p)+"."+str(q)+"."+str(r)+"."+str(s)
> 
> Beyond what other wrote:
> To future-proof code, use // instead of / for integer division.
> To get both quotient and remainder, use divmod(num,den)
> For future reading (and generalization) documenting magic constants helps.
> 
> In 3.0:
> 
> def inet2ip(n):
>   p = (n//16777216)
>   q = ((n-(p*16777216))//65536)
>   r = ((n-((p*16777216)+(q*65536)))//256)
>   s = ((n-((p*16777216)+(q*65536)+(r*256))))
>   return str(p)+"."+str(q)+"."+str(r)+"."+str(s)
> 
> def inet2ip2(n):
>     p,n=divmod(n,16777216) # 1<<24
>     q,n=divmod(n,65536) # 1<<16
>     r,s=divmod(n,256) # 1<<8
>     return str(p)+"."+str(q)+"."+str(r)+"."+str(s)
> 
> print(inet2ip(1000000000), inet2ip2(1000000000))
> 
>>>>
> 59.154.202.0 59.154.202.0
> 
Jeez, doesn't anyone read the fine manual any more? I hope this was just
an academic exercise.

>>> socket.inet_ntoa(struct.pack("!l", 1000000000))
'59.154.202.0'
>>>

Holden's rule: when it looks simple enough to be worth including in the
standard library it may well already *be* in the standard library.

regards
 Steve
-- 
Steve Holden        +1 571 484 6266   +1 800 494 3119
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