# functions in ruby

​

def foo()

    # function body

end

def calculate(num1 = 5, num2 = 3, op = "subtract")

    if (op == "+")

        $output = num1 + num2

    elsif (op == "-")

        $output = num1 - num2

  elsif (op == "*")

        $output = num1 * num2

  elsif (op == "/")

        $output = num1 / num2

  elsif (op == "^")

        $output = num1 ** num2

  else

    $output = "Invalid operation"

  end

end

​

print("Enter a number")

print("\n")

numb1 = gets.chomp.to_i

print("Enter another number")

print("\n")

numb2 = gets.chomp.to_i

print("Enter an operation")

print("\n")

operation = gets.chomp

​

calculate numb1, numb2, operation

puts $output

def double(x)

  x * 2

end