How to convert a string or integer to binary in Ruby?

Question

How do you create integers 0..9 and math operators + - * / in to binary strings. For example:

 0 = 0000,
 1 = 0001, 
 ...
 9 = 1001

Is the

Answer 1

Picking up on bta's lookup table idea, you can create the lookup table with a block. Values get generated when they are first accessed and stored for later:

>> lookup_table = Hash.new { |h, i| h[i] = i.to_s(2) }
=> {}
>> lookup_table[1]
=> "1"
>> lookup_table[2]
=> "10"
>> lookup_table[20]
=> "10100"
>> lookup_table[200]
=> "11001000"
>> lookup_table
=> {1=>"1", 200=>"11001000", 2=>"10", 20=>"10100"}