Converting ip to binary

Question

I am trying to convert 4 entered octets of an IP address into their binary form. This is only part of the code for converting the first octet into its 8 bit form. 'oc' is octet - I will fix variable names when I get this working.

remainder = 0

bits = (128,64,32,16,8,4,2,1)

binary = [0,0,0,0,0,0,0,0]

oc = int(input("Enter oc1: "))
if oc > 256:
    print("Only 256 or less")

if oc > bits[0] or oc == bits[0]:
    binary[0] = 1
    remainder = remainder + oc - bits[0]
    print(binary)
    print(remainder)
elif oc < bits[0]:
    binary[0] = 0
    print(binary)

if remainder > bits[1] or remainder == bits[1]:
    binary[1] = 1
    remainder = remainder - bits[1]
    print(binary)
    print(remainder)
elif oc < bits[1]:
    binary[1] = 0
    print(binary)

if remainder > bits[2] or oc == bits[2]:
    binary[2] = 1
    remainder = remainder - bits[2]
    print(binary)
    print(remainder)
elif oc < bits[2]:
    binary[2] = 0
    print(binary)

When I enter 128 or greater as the octet I get a successful output.

E.g.: Entering '192' will display '1,1,0,0,0,0,0,0' but anything below 128 and the output is all zeros.

I am sure, I could use a loop for most of this as well but do not know how.

i dont see anything about converting an ip to its binary form.. just trying to create this program for a the convenience it'll bring when converting ip to binary @PeterWood — l30n1d45
– l30n1d45, Commented Mar 7, 2015 at 19:46

Tom · Accepted Answer · 2015-03-07 20:29:15Z

2

Will this work for you?

oc = int(input("Enter oc1: "))
if oc > 256:
    print("Only 256 or less")
else:
    binary = bin(oc)[2:]

bin() converts an integer to binary, and using the [2:] appendage drops the leading '0b' you would otherwise get.

If you want to ensure that you have 8 characters, with leading zeros, you can use zfill(). As another appendage, zfill(n) will add leading zeros until your string is n characters long.

binary = bin(oc)[2:].zfill(8)

edited Mar 7, 2015 at 20:29

answered Mar 7, 2015 at 20:05

Tom

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2 Comments

l30n1d45 Over a year ago

being new to python, this method took me by surprise! is there any way to keep the most significant zeros, seeing as there should be 8 bits when converting ip to binary? @Tom thanks!

Tom Over a year ago

Yup, use zfill(). I edited my answer to include it. You should also probably consider including a if oc < 0: print('Non-negatives only'), lest the [2:] will not work perfectly.

Ani Menon · Accepted Answer · 2016-05-15 07:16:45Z

1

Convert a IPv4 address to binary :

ip=raw_input("Enter the ip address\n") #input the ipv4 address
ips=ip.split('.') #split by '.'

for i in ips:  #ips is a list of octets,
 ##we parse through the list to convert each of these to binary
    print(format(int(i),'08b')) #Use format '08b' to add leading '0' to form '8' digits of binary 'b'

Input :

192.95.01.56

Output:

answered May 15, 2016 at 7:16

Ani Menon

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Comments

user2440647 · Accepted Answer · 2015-03-07 20:09:14Z

0

The solution given by @Tom seems most appropriate. But if you want to go to basic school mathematics of converting decimal to binary, one solution is this.

import sys

string = "127.0.0.1"
oc = string.split(".")
for i in range(0, 4) :
   num = int(oc[i]) 
   j = 0;
   remlist = []
   while num > 0 :
       rem = num % 2
       j = j + 1
       remlist.append(rem)
       num = num / 2

   for x in range(j, 8) :
       remlist.append(0)    
   for element in reversed(remlist) :  
       print element,
   if i < 3 :
       print ".",

answered Mar 7, 2015 at 20:09

user2440647

9 Comments

l30n1d45 Over a year ago

python loops confuse me.. what exactly does the 'i' in 'for i in range(0, 4):' mean?

l30n1d45 Over a year ago

python loops confuse me.. what exactly does the 'i' in 'for i in range(0, 4):' mean? @mayankTUM

user2440647 Over a year ago

The function string.split(".") parses the string into an array of strings of size 4. range(0,4) returns a list of integers [0,1,2,3] and 'i' is simply the iterator that loops through all these values. Similar to "for(i = 0; i<4; i++)" in c or java.

l30n1d45 Over a year ago

so the string.split(".") produces the 4 numbers in string without the "."? and if i had this code: train = 1,2,3 for name in train: value = name*10 print(value) what does 'name' stand for in 'for name'? this is an example i saw a while back @mayankTUM

user2440647 Over a year ago

if I understood your question correctly, name will take the value 1 first, then 2 and so on. You will get 10,20,30 as the output.

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