Crystal: Swap Nibbles

In this weekly challenge the task was to swap the lower and upper 4 bits (nibbles) of an integer.

This is my implementation in the Crystal language.

At first I thought to convert the number to its binary representation and do the swapping there, but then I fugured it is just a simple mathematical operation.

• % is modulo
• // is integer division

Below the function I included the code to iterate over the range between 0 and 255 (inclusive) and for each iteration print the binary representation (padded with 0s) and the decimal representation of the original number followed by the decimal representation of the nibble-swapped number.

examples/crystal/swap_nibbles.cr

def swap_nibbles(n)
  return 16 * (n % 16) + (n // 16)
end

#puts swap(101)
#puts swap(18)

(0..255).each {|num|
  puts "%08b %3s %3s" % {num, num, swap_nibbles(num)}
}