Convert (decode) hexadecimal string to binary string

Question

How can I convert "1234567890" to "\x12\x34\x56\x78\x90" in Ruby?

Judging by the answers, the output is supposed to be "\x12\x34\x56\x78\x90", rather than an Array of Fixnum or a syntactically invalid Hash. — Martin Dorey, Jul 26 '13 at 20:55

score 34 · Answer 1 · answered Jan 01 '12 at 18:18

34

Try this:

["1234567890"].pack('H*')

answered Jan 01 '12 at 18:18

patrick

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This is definitely the most elegant solution. The top voted answer will not do what is asked. – Niklas B. Mar 30 '12 at 13:50

Vikrant Chaudhary · Answer 2 · 2012-05-04T05:46:18.667

11

Ruby 1.8 -

hex_string.to_a.pack('H*')

Ruby 1.9 / Ruby 1.8 -

Array(hex_string).pack('H*')

edited May 04 '12 at 05:46

answered Mar 23 '10 at 04:20

Vikrant Chaudhary

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File.open('output.txt', 'w+') {|f| f.write(IO.read('input.txt').to_a.pack('H*')) } – neoneye Jun 24 '10 at 14:47
I'm not sure how your answer is supposed to work. Could you give a better example using the hex string in the question? When I tried your code I got: `d:\>irb irb(main):001:0> hex_string = "1234567890" => "1234567890" irb(main):002:0> hex_string.to_a.pack('H*') NoMethodError: undefined method `to_a' for "1234567890":String from (irb):2 from C:/Ruby192/bin/irb:12:in `
' irb(main):003:0>`
– ZombieDev Oct 05 '11 at 17:12
@ZombieDev, @steenslag Ruby 1.9 doesn't have `String#to_a` method. I've updated my answer to reflect that. – Vikrant Chaudhary May 04 '12 at 05:47

score 8 · Answer 3 · answered Jun 18 '12 at 21:29

Assuming you have a well-formed hexadecimal string (pairs of hex digits), you can pack to binary, or unpack to hex, simply & efficiently, like this:

string = '0123456789ABCDEF'
binary = [string].pack('H*')     # case-insensitive
 => "\x01#Eg\x89\xAB\xCD\xEF"
hex = binary.unpack('H*').first  # emits lowercase
 => "012345679abcdef"

score 4 · Answer 4 · edited Jul 17 '11 at 10:16

4

class String

  def hex2bin
    s = self
    raise "Not a valid hex string" unless(s =~ /^[\da-fA-F]+$/)
    s = '0' + s if((s.length & 1) != 0)
    s.scan(/../).map{ |b| b.to_i(16) }.pack('C*')
  end

  def bin2hex
    self.unpack('C*').map{ |b| "%02X" % b }.join('')
  end

end

edited Jul 17 '11 at 10:16

McDowell

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answered Jul 16 '11 at 19:33

Randy Langer

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score 1 · Answer 5 · answered May 14 '09 at 08:27

1

If you have a string containing numbers and you want to scan each as a numeric hex byte, I think this is what you want:

"1234567890".scan(/\d\d/).map {|num| Integer("0x#{num}")}

answered May 14 '09 at 08:27

Chuck

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I'd have done: "1234567890".scan(/\d\d/).map {|i| i.to_i(16) } – the Tin Man Mar 23 '10 at 09:05
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Or, to handle **hex** characters as requested, `"1234567890abcdef".scan(/[0-9A-Fa-f]{2}/).map { |i| i.to_i(16) }`. – Huw Walters Apr 14 '11 at 10:55

score -1 · Answer 6 · edited Jul 17 '11 at 10:16

-1

(0..4).map { |x| "0x%X" % (("1234567890".to_i(16) >> 8 * x) & 255) }.reverse

edited Jul 17 '11 at 10:16

McDowell

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answered May 14 '09 at 08:25

Kevin Peterson

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Convert (decode) hexadecimal string to binary string

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