First Script Problem

[Brett g Porter]

Ed Hotchkiss wrote:
> This script should just be writing every possibly IP (yea, there are 
> billions i know blah blah) to a txt file. Instead of just writing the 
> IP, it continues and the number goes past 4 groups. IE: The possible IP 
> keeps getting 3 characters longer every time. And at the end of the last 
> loops do I somehow have to set my mySet to NULL? Any ideas here? 
> 
> -- 
> edward hotchkiss
>  
>  

>  
> 
> 
> # Script to Evaluate every possible IP Address Combo, then write it to a 
> text file
> # 9/15/05
> 
> # ipFileLocation = r"G:\Python\myCode\IPList.txt"
> 
> ipFileLocation = "IPList.txt"
> ipFile = open(ipFileLocation, 'w')
> 
> def findIPs():
>  for num in range(256):
>   mySet = "%03.d" % num

okay -- at this point, on the first iteration of this outer loop, mySet 
is '000'

>   for num in range(256):
>    mySet = mySet + "." + "%03.d" % num
and on the first iteration of this first inner loop, mySet is '000.000'

>    for num in range(256):
>     mySet = mySet + "." + "%03.d" % num
second inner loop, first iteration, mySet is '000.000.000'
>     for num in range(256):
>      mySet = mySet + "." + "%03.d" % num
>      ipFile.write(mySet+"\n")

Okay -- this innermost loop will now be executed 256 times (values 
ranging from 0 to 255, and mySet just keeps getting appended to, 
creating the ever-growing output string that you see.

A better way to write this would be something like:

for octet1 in range(256):
    for octet2 in range(256):
       for octet3 in range(256):
          for octet4 in range(256):
             ipAddress = '%03.d.%03.d.%03.d.%03.d\n' % (octet1, octet2, 

                 octet3, octet4)
             ipFile.write(ipAddress)

...which will generate output like you're looking for:

000.000.000.000
000.000.000.001
000.000.000.002
000.000.000.003
000.000.000.004
000.000.000.005
000.000.000.006
000.000.000.007
000.000.000.008
000.000.000.009
000.000.000.010
000.000.000.011
000.000.000.012
000.000.000.013
000.000.000.014

Also note that growing strings by concatenating with '+' is going to 
create code that runs very slowly as the strings continue to grow -- 
much better to either use string formatting or the idiom of using the 
join method of list objects to create a string in a single pop once a 
list of substrings is all populated.


-- 
//  Today's Oblique Strategy (© Brian Eno/Peter Schmidt):
//  Destroy -nothing -the most important thing
//  Brett g Porter * BgPorter at acm.org
//  http://bgporter.inknoise.com/JerseyPorkStore