RSpec
Ruby on Rails
Ruby
method
bit_length
Ruby latest stable (v2_5_5)
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= private
= protected
bit_length()
public
Returns the number of bits of the value of int.
“the number of bits” means that the bit position of the highest bit which is different to the sign bit. (The bit position of the bit 2**n is n+1.) If there is no such bit (zero or minus one), zero is returned.
I.e. This method returns ceil(log2(int < 0 ? -int : int+1)).
(-2**10000-1).bit_length #=> 10001 (-2**10000).bit_length #=> 10000 (-2**10000+1).bit_length #=> 10000 (-2**1000-1).bit_length #=> 1001 (-2**1000).bit_length #=> 1000 (-2**1000+1).bit_length #=> 1000 (2**1000-1).bit_length #=> 1000 (2**1000).bit_length #=> 1001 (2**1000+1).bit_length #=> 1001 (2**10000-1).bit_length #=> 10000 (2**10000).bit_length #=> 10001 (2**10000+1).bit_length #=> 10001
This method can be used to detect overflow in Array#pack as follows.
if n.bit_length < 32 [n].pack("l") # no overflow else raise "overflow" end
