how to translate base 10 number into base 2 number

[chen li]

Hi all,

I want to write a method to tranlate base 10 number
into base 2 number. I want to call the method within
itself. But it doesn't work. What is the right way
to do something like this?

Thanks,

Li

#####
def ten_to_two(num1)
@array=[]
if num1>2
first,second=num1.divmod(2)
@array<<second

#call the method itself
ten_to_two(first)

else
@array<<second<<first
end
return @array.reverse
end

puts ten_to_two(5)

##output

ruby assembly1.rb nil
nil
Exit code: 0

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[Eric I.]

Hi Li,

First, here's a solution:

def ten_to_two(num1)
return [] if num1 <= 0
first,second=num1.divmod(2)
ten_to_two(first) << second
end

And note that you can change the << into a call to unshift if you want
the bits in the reverse order.

As for why your solution didn't work, let me offer two things. First,
you never do anything with the result of your recursive call to
ten_to_two. Somehow you need to combine it with the partial result you
calculated immediately beforehand. Second, you're using instance
variables (tagged with the @). That's generally done in methods
defined within a class to hold the state of the instance. For a
"naked" method, you generally stick to local variables (no @).

Eric

================
Interested in hands-on, on-site Ruby training? See www.LearnRuby.com
for information about a well-reviewed class.

Hi all,

I want to write a method to tranlate base 10 number
into base 2 number. I want to call the method within
itself. But it doesn't work. What is the right way
to do something like this?

Thanks,

Li

#####
def ten_to_two(num1)
@array=[]
if num1>2
first,second=num1.divmod(2)
@array<<second

#call the method itself
ten_to_two(first)

else
@array<<second<<first
end
return @array.reverse
end

puts ten_to_two(5)

##output

ruby assembly1.rb nil
nil
Exit code: 0

 

[khaines]

Hi all,

I want to write a method to tranlate base 10 number
into base 2 number. I want to call the method within
itself. But it doesn't work. What is the right way
to do something like this?

This doesn't answer your question, but in case you were not aware, Ruby
will do this conversion for you:


a = 125
puts a.to_s(2)
1111101


Kirk Haines

 

[Uma Geller]

TAWLWTDIT

[0xFF].pack("c").unpack("b8")

there's a whole lotta ways to do it

This doesn't answer your question, but in case you were not aware, Ruby
will do this conversion for you:


a = 125
puts a.to_s(2)
1111101


Kirk Haines

 

[Robert Klemme]

TAWLWTDIT

[0xFF].pack("c").unpack("b8")

there's a whole lotta ways to do it

Since we start collecting solutions...

irb(main):001:0> "%b" % 16
=> "10000"



robert

 

[Uma Geller]

Since we start collecting solutions...

irb(main):001:0> "%b" % 16
=> "10000"

readable and concise
beautiful !

UG

 

[Giles Bowkett]

I wonder why there isn't support for negative radix; even though the
solutions might not be unique... who cares?

Come on, that's like asking why fractional dimension isn't a primitive
type in Java.