Passing a splat parameter from one method to another method

Question

I would like to create methods called 'add' and 'subtract' using splat parameter as below:

def add(*numbers)
  numbers.inject(0) { |sum, n| sum + n }
end

def subtract(*numbers)
  numbers[0] - add(numbers[1..-1])
end

But it didn't work. What should I do to pass the splat parameter from one to another? (Especially for some specific range...)

Thank you!

Answer 1

When you call add function, add * before the array object to unpack array as multiple arguments.

def add(*numbers)
  numbers.inject(0) { |sum, n| sum + n }
end

def subtract(*numbers)
  numbers[0] - add(*numbers[1..-1])
  #                ^
end

subtract(9, 0, 1, 2) # => 6
subtract(9, 1) # => 8