Ruby to_bytes reverse function needed

Question

I have this function from github or whatever:

class String
  def to_bytes
    (0...self.length/2).map {|i|self[i*2,2].to_i(16)}
  end
end

and my point is, that I am not really sure what is the whole thing doing, especially the self[something] part and please can somebody help me to reverse this procedure? I am not experienced and I kind of desperately need to get those numbers back into string.

Thanks a lot

I'll try to explain the method in as plain English as I can. (0...self.length/2) returns a number that is half the string's length. (self is a keyword that means, in the context of a method like to_bytes, the string upon which to_bytes is being requested.) map takes the number (half the string's length), takes two characters from the string at a time, and converts each pair to hex, and places the result in an array. — maxenglander
– maxenglander, Commented Oct 10, 2011 at 13:20

maxenglander · Accepted Answer · 2011-10-10 13:46:07Z

2

I don't think you can reliably convert the result of to_bytes back to the original string. Both "a".to_bytes and "b".to_bytes will produce [0]. However, assuming that this isn't a problem for you, the reverse of your to_bytes method would be something like this:

def reverse_string_to_bytes bytes
  result = ""
  bytes.each do |pair|
    result << pair.to_s(16)
  end
end

answered Oct 10, 2011 at 13:46

maxenglander

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1 Comment

Redrick Over a year ago

I see, this things does pretty much nothing at all, but when I look at the "a".to_bytes and some other examples, the to_bytes ruins the whole input... still wondering why would somebody do that, cause I am modifying code of someone else, but thanks for your time, I appreciate it.

Volte · Accepted Answer · 2016-06-13 18:20:30Z

-1

Seems like much to do about nothing...

Why don't you just

"My string".bytes.reverse
# Or
def reverse_bytes(str)
    str.bytes.reverse
end

answered Jun 13, 2016 at 18:20

Volte

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