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Contents
defmodule Hexadecimal do
@base 16
@hex_table String.split("0123456789abcdef", "", trim: true)
|> Enum.with_index
|> Enum.into(%{})
@doc """
Accept a string representing a hexadecimal value and return the
corresponding decimal value.
It returns the integer 0 if the hexadecimal is invalid.
Otherwise returns an integer representing the decimal value.
## Examples
iex> Hexadecimal.to_decimal("invalid")
0
iex> Hexadecimal.to_decimal("af")
175
"""
@spec to_decimal(binary) :: integer
def to_decimal(hex) do
if invalid?(hex) do
0
else
hex
|> String.downcase
|> String.reverse
|> String.split("", trim: true)
|> hex_to_int(0, 0)
end
end
defp invalid?(hex) do
String.match?(hex, ~r/[^0-9a-fA-F]/)
end
defp hex_to_int([], acc, _), do: round(acc)
defp hex_to_int([char|hex], acc, power) do
acc = acc + Map.get(@hex_table, char) * :math.pow(@base, power)
hex_to_int(hex, acc, power + 1)
end
end
Version data entries
327 entries across 327 versions & 1 rubygems