Ruby on Rails Coding Interview Question: Decimal Number To Binary

Ruby on Rails Coding Interview Question: Decimal Number To Binary

Here’s a Ruby method to convert a decimal number to binary without any in-built methods.

def decimal_to_binary(decimal_number)
  return '0' if decimal_number == 0

  binary = ''
  while decimal_number > 0
    binary = (decimal_number % 2).to_s + binary
    decimal_number /= 2
  end

  return binary
end


# Output
puts decimal_to_binary(10) # Output: "1010"
puts decimal_to_binary(42) # Output: "101010"
puts decimal_to_binary(255) # Output: "11111111"

Let’s go through the implementation line by line and explain what each line does using a detailed example,

def decimal_to_binary(decimal_number)
  return '0' if decimal_number == 0

In this line, we define a method called decimal_to_binary that takes a decimal_number as input. If the decimal_number is equal to 0, we return the string '0' because the binary representation of 0 is simply '0'.

  binary = ''

We initialize an empty string called binary. This variable will store the binary representation of the decimal_number.

  while decimal_number > 0

We enter a while loop that will continue as long as the decimal_number is greater than 0. This loop will help us extract the binary digits from the decimal number.