习题 21 函数可以返回某些东西

# ex21.rb

def add(a, b)
    puts "ADDING #{a} + #{b}"
    return a + b
end

def subtract(a, b)
    puts "SUBTRACTING #{a} - #{b}"
    return a - b
end

def multiply(a, b)
    puts "MULTIPLYING #{a} * #{b}"
    return a * b
end

def divide(a, b)
    puts "DIVIDING #{a} / #{b}"
    return a / b
end

puts "Let's do some math with just functions!"

age = add(30, 5)
height = subtract(78, 4)
weight = multiply(90, 2)
iq = divide(100, 2)

puts "Age: #{age}, Height: #{height}, Weight: #{weight}, IQ: #{iq}"

puts "Here is a puzzle."

what = add(age, subtract(height, multiply(weight, divide(iq, 2))))

puts "That becomes: #{what}. Can you do it by hand?"

结果：

$ ruby ex21.rb
Let's do some math with just functions!
ADDING 30 + 5
SUBTRACTING 78 - 4
MULTIPLYING 90 * 2
DIVIDING 100 / 2
Age: 35, Height: 74, Weight: 180, IQ: 50
Here is a puzzle.
DIVIDING 50 / 2
MULTIPLYING 180 * 25
SUBTRACTING 74 - 4500
ADDING 35 + -4426
That becomes: -4391. Can you do it by hand?