# How many IP addresses are in a given range?

Inspired by...

Networking - How can I work out how many IP addresses there are in a given range?

Write a program or function that takes two strings as input, each being an IPv4 address expressed in standard dotted notation and outputs or returns the number of IP addresses covered by this range, including the two IP addresses input.

• You must not use any external code, libraries or services designed to parse an IP address. (Other string processing standard library functions are acceptable.)
• Normal code-golf rules apply.

For example:

"0.0.0.0","255.255.255.255" returns 4294967296.
"255.255.255.255","0.0.0.0" also returns 4294967296.
"1.2.3.4","1.2.3.4" returns 1.
"56.57.58.59","60.61.62.63" returns 67372037.
"1","2" is invalid input. Your code may do anything you like.

• I saw this question on programmers, and was thinking about asking it on code golf lol. May 30, 2014 at 14:59
• I thought this is a StackOverflow question about what IP addresses are impossible according to the standards. May 30, 2014 at 18:30
• Isn't IPv4 a bit passe? May 31, 2014 at 8:37

# GolfScript, 20 bytes

~]7/${2%256base}/)\-  Try it online. ### Test cases $ echo 0.0.0.0 255.255.255.255 | golfscript range.gs
4294967296
$echo 255.255.255.255 0.0.0.0 | golfscript test.gs 4294967296$ echo 1.2.3.4 1.2.3.4 | golfscript test.gs
1
$echo 56.57.58.59 60.61.62.63 | golfscript test.gs 67372037  ### How it works ~] # Evaluate and collect into an array. # # “.” duplicates, so for "5.6.7.8 1.2.3.4", this leaves # [ 5 5 6 6 7 7 8 1 1 2 2 3 3 4 ] on the stack. # 7/ # Split into chunks of length 7: [ [ 5 5 6 6 7 7 8 ] [ 1 1 2 2 3 3 4 ] ]$         # Sort the array of arrays: [ [ 1 1 2 2 3 3 4 ] [ 5 5 6 6 7 7 8 ] ]
{         # For each array:
2%      # Extract every second element. Example: [ 1 2 3 4 ]
256base # Convert the IP into an integer by considering it a base 256 number.
}/        #
)         # Add 1 to the second integer.
\-        # Swap and subtract. Since the integers were sorted, the result is positive.

• Very nice, and nice use of $ to avoid abs. May 30, 2014 at 6:26 • ~] is also really clever. May 30, 2014 at 7:23 # Python 2 - 106 See it here. def a():x=map(int,raw_input().split("."));return x*2**24+x*2**16+x*2**8+x print abs(a()-a())+1  Example Input 0.0.0.0 0.0.0.255 Example Output 256 • def a():return reduce(lambda c,d:c*256+d,map(int,raw_input().split("."))) is a lot shorter May 29, 2014 at 20:37 • @Michael Thanks for the suggestion. I used it for a few minutes, then looked at it and thought, "I didn't write 90% of that." so I rolled it back. May 29, 2014 at 20:50 • @Michael a=lambda: instead of def a():return  saves 6 characters May 30, 2014 at 11:41 • @Rusher It's 107 characters, not 106 May 30, 2014 at 11:44 • @avall: I assume you're counting the final LF. May 30, 2014 at 13:36 # CJam - 15 {r'./256b}2*-z)  Try it at http://cjam.aditsu.net/ Thanks Dennis, wow, I don't know how to get the best out of my own language :p • You can save two bytes by eliminating :i (b seems to cast to integer) and one by using {r...}2* instead of qS/{...}/ Jun 2, 2014 at 22:12 # Pure bash, 66 bytes p()(printf %02x${1//./ })
r=$[0xp$1-0xp $2] echo$[1+${r/-}]  Notes: • Defines a function p that is passed a dotted decimal IP address, and outputs the hex representation of that address: • ${1//./ } is a parameter expansion that replaces . with   in the IP address passed to p()
• The printf is mostly self explanatory. Since there is only one format specifier %02x and four remaining args, the format specifier is reused for each remaining arg, effectively concatenating the 2 hex digits of each of the 4 octets together
• $[] causes arithmetic expansion. We do a basic subtraction, and assign to the variable r • ${r/-} is a parameter expansion to remove a possible - character - effectively abs()
• Display 1 + the absolute difference to give the range.

Output:

$./iprangesize.sh 0.0.0.0 255.255.255.255 4294967296$ ./iprangesize.sh 255.255.255.255 0.0.0.0
4294967296
$./iprangesize.sh 1.2.3.4 1.2.3.4 1$ ./iprangesize.sh 56.57.58.59 60.61.62.63
67372037
$./iprangesize.sh 1 2 2$

• I detect printf and echo. Are those part of bash? Apr 11, 2016 at 0:34
• @CatsAreFluffy They're builtins.
Apr 11, 2016 at 3:21

## Python 2.7 - 969190 87

f=lambda a:reduce(lambda x,y:x*256+int(y),a.split("."),0)
p=lambda a,b:abs(f(a)-f(b))+1


Usage:

>>> p("1.2.3.4","1.2.3.5")
2


Edit: Removed unnecessary int() from f function. Thanks to isaacg

Edit2: Removed LF at the end of file (thanks to @Rusher) and removed map() at cost of reduce() initializer (thanks to @njzk2)

• why does the f function need int() on the outside? May 30, 2014 at 7:14
• Well. I had no idea :D May 30, 2014 at 7:23
• can gain 2 chars by putting the int in the reduce instead of using the map (only 2 as you need to add ,0 parameter to your reduce function) May 30, 2014 at 14:26
• I just wrote something that is almost exactly your code, so I won't bother submitting now. Actually, mine is three characters longer! Mar 24, 2015 at 13:51

# CoffeeScript - 94, 92, 79, 72

I=(a)->a.split(".").reduce((x,y)->+y+x*256)
R=(a,b)->1+Math.abs I(b)-I a


Un-golfed:

I = ( a ) ->
return a.split( "." ).reduce( ( x, y ) -> +y + x * 256 )

R = ( a, b ) ->
return 1 + Math.abs I( b ) - I( a )


Equivalent JavaScript:

function ip2long( ip_str )
{
var parts = ip_str.split( "." );
return parts.reduce( function( x, y ) {
return ( +y ) + x * 256; //Note: the unary '+' prefix operator casts the variable to an int without the need for parseInt()
} );
}

function ip_range( ip1, ip2 )
{
var ip1 = ip2long( ip1 );
var ip2 = ip2long( ip2 );

return 1 + Math.abs( ip2 - ip1 );
}

• You can save some characters by replacing some parentheses with spaces: I=(a)->n=0;a.split(".").forEach((x)->n<<=8;n+=parseInt x);n>>>0 R=(a,b)->1+Math.abs I(b)-I a May 29, 2014 at 20:48
• It feels like you're losing a lot of space to Math.abs, but I can't come up with anything shorter. (z>0)*z||-z is the best I've got (same length, and it needs a single-char input). Do you have anything cleverer than that? May 30, 2014 at 21:07
• this javascript version really helps me, ive been searching for this for like an hour. thanks! May 13, 2019 at 7:27

## GolfScript, 27 bytes

' '/{'.'/{~}%256base}/-abs)


Examples:

$echo 0.0.0.0 255.255.255.255 | ruby golfscript.rb iprange.gs 4294967296$ echo 255.255.255.255 0.0.0.0 | ruby golfscript.rb iprange.gs
4294967296
$echo 1.2.3.4 1.2.3.4 | ruby golfscript.rb iprange.gs 1$ echo 56.57.58.59 60.61.62.63 | ruby golfscript.rb iprange.gs
67372037

• You can save one char by using / instead of %~. May 30, 2014 at 5:21

# Perl, 43 bytes

#!perl -pa
$_=1+abs${\map{$_=vec eval,0,32}@F}-$F


Counting the shebang as two bytes.

Sample Usage:

$echo 0.0.0.0 255.255.255.255 | perl count-ips.pl 4294967296$ echo 255.255.255.255 0.0.0.0 | perl count-ips.pl
4294967296

$echo 56.57.58.59 60.61.62.63 | perl count-ips.pl 67372037  Notes • vec eval,0,32 is a drop-in for ip2long. Perl allows character literals to be expressed as their ordinal prefixed with a v, for example v0 can be used for the null char. These can also be chained together, for example v65.66.67.68ABCD. When three or more values are present, the initial v is unnecessary. The vec function interprets a string as an integer array, each cell having the specified number of bits (here, 32). unpack N,eval would have worked equally as well. # dc, 61 characters ?[dXIr^*rdXIr^*256*+r1~dXIr^*r256*+65536*+]dspxsalpxla-d*v1+p  I think it's pretty amazing that this can be solved with dc at all since it has no ability to parse strings. The trick is that 192.168.123.185 goes on the stack as .185 .123 192.168  and dXIr^* shifts the decimal point right as many fraction digits as there are and it even works for .100. $ echo 56.57.58.59 60.61.62.63 | dc -e '?[dXIr^*rdXIr^*256*+r1~dXIr^*r256*+65536*+]dspxsalpxla-d*v1+p'
67372037.00


Subtract a character if you let the input already be on the stack.

# Powershell - 11210892 78 bytes

This is my first time golfing. Here goes nothing:

### Golfed (Old):

$a,$b=$args|%{$t='0x';$_-split'\.'|%{$t+="{0:X2}"-f[int]$_};[uint32]$t};1+[math]::abs($a-$b)


### Golfed (new)

$a,$b=$args|%{$t='0x';$_-split'\.'|%{$t+="{0:X2}"-f+$_};[long]$t}|sort;1+$b-$a


### Ungolfed:

$a,$b = $args | % { #powershell's way of popping an array. In a larger array #$a would equal the first member and $b would be the rest.$t = '0x';                 #string prefix of 0x for hex notation
$_ -split '\.' | % { #split by escaped period (unary split uses regex)$t += "{0:X2}" -f +$_ #convert a dirty casted int into a hex value (1 octet) }; [long]$t                   #and then cast to long
} | sort;                      #sort to avoid needing absolute value
1 + $b -$a                    #perform the calculation


### Usage

Save as file (in this case getipamount.ps1) and then call from the console

getipamount.ps1 255.255.255.255 0.0.0.0


# C# with LINQ - 139 bytes

(From 140 after applying Bob's suggestion.)

long f(params string[] a){return Math.Abs(a.Select(b=>b.Split('.').Select(long.Parse).Aggregate((c,d)=>c*256+d)).Aggregate((e,f)=>e-f))+1;}


Ungolfed....

    long f(params string[] a)                           // params is shorter than two parameters.
{
return Math.Abs(                                // At the end, make all values +ve.
a.Select(                                  // Go through both items in the array...
b =>                                    // Calling each one 'b'.
b.Split('.')                        // Separating out each "." separated byte...
.Select(long.Parse)                 // Converting them to a long.
.Aggregate((c, d) => c*256 + d)     // Shift each byte along and add the next one.
)
.Aggregate((e,f) => e-f)                   // Find the difference between the two remaining values.
)+1;                                           // Add one to the result of Math.Abs.
}


https://dotnetfiddle.net/XPTDlt

• Could someone explain to me how this whole shifting bytes along thing works? May 30, 2014 at 0:31
• @Obversity a.b.c.d is equivalent to (a << 24) | (b << 16) | (c << 8) | (d << 0) is equivalent to (((a << 8) << 8) << 8) + ((b << 8) << 8) + (c << 8) + d). Basically, each iteration of the aggregation takes the existing sum and shifts it left by one octet, then adds the next octet.
– Bob
May 30, 2014 at 1:04
• You can save a character by using c*256 instead of (c<<8).
– Bob
May 30, 2014 at 1:13
• @Bob Well spotted. May 30, 2014 at 7:54
• You can save two more characters by replacing e-f with e<f?f-e:e-f and dropping the Math.Abs() May 30, 2014 at 10:06

## JavaScript ES6 - 68 bytes

f=x=>prompt().split('.').reduce((a,b)=>+b+a*256);1+Math.abs(f()-f())


Try it with the console (press F12) of Firefox.

• You should be using alert or console.log. Console output is cheap. May 29, 2014 at 20:24
• @nderscore, absolutely no difference between console.log and direct output. This is code-golf, it's not about do clean code. May 29, 2014 at 20:31
• The most upvoted answer to this meta post disagrees: JavaScript Standards for IO. It's not a matter of clean code. It's a matter of not actually outputting anything. May 29, 2014 at 20:57
• @DigitalTrauma, it won't work due to operator precedence. (addition vs bitwise shift) May 29, 2014 at 22:29

# Python 2.7, 104 bytes

y=lambda:map(int,input().split("."));a,b=y(),y();print sum(256**(3-i)*abs(a[i]-b[i])for i in range(4))+1

• Thanks for the solution. Do you think you could: 1. Switch from semicolons to newlines, for readability without sacrificing length. 2. Explain how the code works? Mar 22, 2015 at 7:58

# Perl, 72 bytes

#!perl -ap
@a=map{unpack N,pack C4,split/\./,$_}@F;$_=abs($a-$a)+1


Usage:

$echo 10.0.2.0 10.0.3.255 | perl ip-range.pl 512$


This is already longer than primo's Perl program, so not too interesting.

# Perl, 119 bytes, for obsolete IP address format

#!perl -ap
sub v(){/^0/?oct:$_}@a=map{$m=3;@p=split/\./,$_;$_=pop@p;$s=v;$s+=v<<8*$m--for@p;$s}@F;$_=abs($a-$a)+1  Usage: $ echo 10.0.2.0 10.0.3.255 | perl ip-obsolete.pl
512 echo 10.512 10.1023 | perl ip-obsolete.pl
512 echo 0xa.0x200 012.01777 | perl ip-obsolete.pl
512$ This program accepts the obsolete format for IP addresses! This includes addresses with 1, 2, or 3 parts, or with hexadecimal or octal parts. Quoting the inet_addr(3) manual page, Values specified using dot notation take one of the following forms: a.b.c.d a.b.c a.b a  ... When a three part address is specified, the last part is interpreted as a 16-bit quantity and placed in the rightmost two bytes of the network address. ... When a two part address is supplied, the last part is interpreted as a 24-bit quantity and placed in the rightmost three bytes of the network address. ... When only one part is given, the value is stored directly in the network address without any byte rearrangement. All numbers supplied as parts'' in a dot notation may be decimal, octal, or hexadecimal, as specified in the C language (i.e., a leading 0x or 0X implies hexadecimal; a leading 0 implies octal; otherwise, the number is interpreted as decimal). Most programs no longer accept this obsolete format, but ping 0177.1 still worked in OpenBSD 5.5. • The fact you're using BSD is more surprising than the IP thing. – jado Apr 11, 2016 at 3:22 # PHP, 138 110 bytes <?php function d($a,$b){foreach(explode('.',"$a.$b")as$i=>$v){$r+=$v*(1<<24-$i%4*8)*($i<4?1:-1);}return 1+abs($r);}

// use it as
d('0.0.0.0','255.255.255.255');

• As there's no mention of 'no deprecation warnings', you can save a char by replacing explode('.',"$a.$b") with split('\.',"$a.$b"). Jun 2, 2014 at 10:22
• I count 109, not 110. Save 9 bytes with a program instead of a function and 8 more with these golfing steps: sandbox.onlinephpfunctions.com/code/… Mar 13, 2017 at 13:24

# Mathematica 9, 108 bytes

c[f_,s_]:=1+First@Total@MapIndexed[#1*256^(4-#2)&,First@Abs@Differences@ToExpression@StringSplit[{f,s},"."]]


Ungolfed:

countIpAddresses[first_, second_] := Module[{digitArrays, differences},

(* Split the strings and parse them into numbers.
Mathematica automatically maps many/most of its functions across/
through lists *)

digitArrays = ToExpression[StringSplit[{first, second}, "."]];

(* Find the absolute value of the differences of the two lists,
element-wise *)
differences = Abs[Differences[digitArrays]];

(* differences looks like {{4, 4, 4, 4}} right now,
so take the first element *)
differences = First[differences];

(* now map a function across the differences,
taking the nth element (in code, '#2') which we will call x (in
code, '#1') and setting it to be equal to (x * 256^(4-n)).
To do this we need to track the index, so we use MapIndexed.
Which is a shame,
because Map can be written '/@' and is generally a huge character-
saver. *)
powersOf256 = MapIndexed[#1*256^(4 - #2) &, differences];

(* now we essentially have a list (of singleton lists,
due to MapIndexed quirk) which represents the digits of a base-256,
converted to decimal form.
Example: {{67108864},{262144},{1024},{4}}

We add them all up using Total,
which will give us a nested list as such: {67372036}

We need to add 1 to this result no matter what. But also,
to be fair to the challenge, we want to return a number -
not a list containing one number.
So we take the First element of our result. If we did not do this,
we could chop off 6 characters from our code. *)

1 + First[Total[powersOf256]]
]


# PHP, 46 Bytes

<?=abs(ip2long($argv)-ip2long($argv))+1;


Try it online!

ip2long

## C# - 135

long f(string x,string y){Func<string,long>b=s=>s.Split('.').Select((c,i)=>long.Parse(c)<<(3-i)*8).Sum();return Math.Abs(b(x)-b(y))+1;}


Properly formatted

long g(string x, string y) {
Func<string, long> b = s => s.Split('.').Select((c, i) => long.Parse(c) << (3 - i) * 8).Sum();
return Math.Abs(b(x) - b(y)) + 1;
}


https://dotnetfiddle.net/Q0jkdA

• Suggest 24-i*8 instead of (3-i)*8 and return-~Math.Abs(b(x)-b(y)) instead of return Math.Abs(b(x)-b(y))+1 Nov 25, 2022 at 11:58

# Ruby, 93 bytes

a=->(x){s=i=0;x.split('.').map{|p|s+=256**(3-i)*p.to_i;i+=1};s}
s=->(x,y){1+(a[x]-a[y]).abs}


Output

irb(main):003:0> s['1.1.1.1', '1.1.1.2']
=> 2
irb(main):006:0> s['0.0.0.0', '255.255.255.255']
=> 4294967296


# J, 25 bytes

Takes the dotted-quad IP strings as left and right arguments.

>:@|@-&(256#.".;.2@,&'.')


Explained:

>:@|@-&(256#.".;.2@,&'.')  NB. ip range
&(                )  NB. on both args, do:
,&'.'   NB.   append a .
;.2@        NB.   split by last character:
".            NB.     convert each split to number
256#.              NB. convert from base 256
|@-                     NB. absolute difference
>:@                        NB. add 1 to make range inclusive


Examples:

   '0.0.0.0' >:@|@-&(256#.".;.2@,&'.') '255.255.255.255'
4294967296
iprange =: >:@|@-&(256#.".;.2@,&'.')
'255.255.255.255' iprange '0.0.0.0'
4294967296
'1.2.3.4' iprange '1.2.3.4'
1
'56.57.58.59' iprange '60.61.62.63'
67372037


# Factor, 73 bytes

[ "." split [ 10 base> ] [ [ 256 * ] dip + ] map-reduce ] bi@ - abs 1 + ]


# Javascript ES6, 81 chars

(a,b)=>Math.abs(eval((((((${a})>>>0)-(((((${b})>>>0).replace(/\./g,")<<8|")))+1


Test:

f=(a,b)=>Math.abs(eval((((((${a})>>>0)-(((((${b})>>>0).replace(/\./g,")<<8|")))+1
;0.0.0.0,255.255.255.255,4294967296
255.255.255.255,0.0.0.0,4294967296
1.2.3.4,1.2.3.4,1
56.57.58.59,60.61.62.63,67372037.split
.map(x=>x.split,).every(x=>f(x,x)==x)


PS: I'll try to optimise it a bit later.

## Lua, 153 Bytes

It's a shame that lua doesn't have a split function, I had to define mine!

a,b=...r=0y=8^8x={}t={}function f(t,s)s:gsub("%d+",function(d)t[#t+1]=d end)end
f(x,a)f(t,b)for i=1,4 do r=r+y*math.abs(t[i]-x[i])y=y/256 end print(r+1)


### Ungolfed

a,b=...                    -- unpack the arguments into two variables
r=0                        -- initialise the sume of ip adress
y=8^8                      -- weight for the rightmost value
x={}t={}                   -- two empty arrays -> will contains the splittedip adresses
function f(t,s)            -- define a split function that takes:
--   a pointer to an array
--   a string
s:gsub("%d+",function(d) -- iterate over the group of digits in the string
t[#t+1]=d              -- and insert them into the array
end)
end
f(x,a)                     -- fill the array x with the first address
f(t,b)                     -- fill the array t with the second address
for i=1,4                  -- iterate over t and x
do
r=r+y*math.abs(t[i]-x[i])-- incr r by weight*abs(range a- range b)
y=y/256                  -- reduce the weight
end
print(r+1)                 -- output the result


# Jelly, 12 bytes, language postdates challenge

ṣ”.V€ḅ⁹µ€ạ/‘


Try it online!

## Explanation

ṣ”.V€ḅ⁹µ€ạ/‘
µ€     On each element of input:
ṣ”.             Split on periods
V€           Convert string to number in each section
ḅ⁹         Convert base 256 to integer
ạ/   Take absolute difference of the resulting integers
‘  Increment


The number of elements in an inclusive range is the absolute difference of their endpoints, plus 1.

# Axiom, 385 bytes

c(a:String):INT==(d:=digit();s:NNI:=#a;t:INT:=0;for i in 1..s repeat(~member?(a.i,d)=>return-1;t:=t+(ord(a.i)-48)*10^(s-i)::NNI);t)
g(x:String):List NNI==(a:=split(x,char".");s:NNI:=#a;r:=[];for i in s..1 by -1 repeat(y:=c(a.i);y=-1=>return [];r:=concat(y,r));r)
m(x:NNI,y:NNI):NNI==x*256+y
f(a:String,b:String):INT==(x:=g(a);y:=g(b);#x~=4 or #y~=4=>-1;1+abs(reduce(m,x)-reduce(m,y)))


ungolf it and test

-- convert the string only digit a in one not negative number
-- return -1 in case of error
cc(a:String):INT==
d:=digit();s:NNI:=#a;t:INT:=0
for i in 1..s repeat
~member?(a.i,d)=>return -1
t:=t+(ord(a.i)-48)*10^(s-i)::NNI
t

-- Split the string x using '.' as divisor in a list of NNI
-- if error return []
gg(x:String):List NNI==
a:=split(x,char".");s:NNI:=#a;r:=[]
for i in s..1 by -1 repeat
y:=cc(a.i)
y=-1=>return []
r:=concat(y,r)
r

mm(x:NNI,y:NNI):NNI==x*256+y

-- Return absolute value of difference of address for IP strings in a and in b
-- Retrun -1 for error
-- [Convert the IP strings in a and in b in numbers ad subtract and return the difference]
ff(a:String,b:String):INT==(x:=gg(a);y:=gg(b);#x~=4 or #y~=4=>-1;1+abs(reduce(mm,x)-reduce(mm,y)))

(14) -> f("0.0.0.0", "255.255.255.255")
(14)  4294967296
Type: PositiveInteger
(15) -> f("255.255.255.255", "0.0.0.0")
(15)  4294967296
Type: PositiveInteger
(16) -> f("1.2.3.4", "1.2.3.4")
(16)  1
Type: PositiveInteger
(17) -> f("56.57.58.59", "60.61.62.63")
(17)  67372037
Type: PositiveInteger
(18) -> f("1", "2")
(18)  - 1
Type: Integer