Reversing base numbers

Question

Where input is binary - output the decimal reversed equivalent and vice versa for decimal input:

Sample Input:

00000001
00000010
255
00011000

Sample Output

1
2
1000101000
42

other Sample Input

78
35
01011001
231

other Sample Output

01010111
00110101
98
10000100  

Answer 1

Ruby, 68 characters

puts$<.map{|i|i[/[^01\s]/]?"%08b"%i.reverse: i.to_i(2).to_s.reverse}

Uses stdin/stdout, interprets lines that consist only of 1s, 0s and whitespace as binary numbers, everything else as decimal.

Answer 2

perl - 90 89

map{print reverse(/^[01]+$/?unpack"N",pack"B*",sprintf"%032d",$_:sprintf"%b",$_).$/}@ARGV

Any number containing only 1's and 0's is considered binary.

Funny how so much more code is required for bin->dec vs. dec->bin...

Answer 3

JavaScript, 140 199 bytes

(function(x){s=x.split("\n"),r=b='';for(i in s)r+='\n'+(s[i].replace(/[01]*/g,b)?
(s[i].split(b).reverse().join(b)-0).toString(2):(parseInt(s[i],2)+"")
.split(b).reverse().join(b));return r.trim()})('1\n10\n255\n11000')

Excluding input. It requires, however, that there are no numbers present in the input which are base 10 and only have 1s / 0s in them.

Answer 4

Python - 117 characters

while 1:
 x=raw_input()
 if(not(False in map(lambda x:x in ("1","0"),s))):print int(x,2)
 else:print bin(int(x))[2:]

This golf relies heavily on the fact that python counts a single space as a full indentation. Note that this golf IS NOT ERROR-PROOF. While functional, it will throw an EOFError when there is no input. Protecting against this requires an extra 30 characters.

Changelog

v0 - 120 chars

v1 - 117 chars - changes "While True" to "While 1"

Answer 5

Quite frankly, i still don't get the testcase for 255, i'll mend my solution when the OP corrects/expands the description.

My Solution is based of rmckenzie

Python - 84 bytes

while 1:
 x=raw_input()
 print all(i<"2"for i in x)and int(x,2)or bin(int(x))[2::]

Answer 6

bash 67

b(){ [[ $1 =~ ^[01]*$ ]]&& s="i"||s="o";echo $s"base=2;$1"|bc|rev;}

Answer 7

J, 60 characters

((1&":@#:@(10&#.@|.)`(|.@":@#.))@.(0=[:+/1<[))".;' ',.1!:1[1