控制流python

Question

其实我已经习惯了 c++ 并且我被困在了 python 中。我似乎无法理解导致无限 while 循环的原因。 代码的主要目标是计算需要多少个月才能节省足够的预付款。

#*******Initializing all the required variables***********
home_price = float(input("Enter the price of your dream home:")) # cost of the home

down_payment_portion = 0.25 # initial upfront pay for the home which is 25%
stamp_duty_portion = 0.03 # 3%

annual_salary = float(input("Enter your annual salary:"))

tax_portion = 0.2 # 20%
save_amount = 0

save_portion = float(input("Enter the amount of money you want to save after tax-cut:"))

annual_return = 0.05 # 5%
months = 0

#*********************************************************
#------------Calculating all the necessary values---------

down_payment_portion = down_payment_portion * home_price # calculating the down payment for the dream home

stamp_duty_portion = stamp_duty_portion * home_price # calculating the stamp duty for the home

tax_portion = tax_portion * annual_salary # calculating the tax cut

save_portion = save_portion * save_amount # calculating the portion of tax-cut income to be put into savings

annual_return = (save_amount * annual_return) / 12

upfront_payment = down_payment_portion + stamp_duty_portion

while(save_amount < upfront_payment):
   save_amount = save_amount + annual_return
   save_amount = save_amount + (annual_salary - tax_portion) * save_portion / 12
   months = months + 1

print(f'You will need {months} month to save enough for your upfront payment{upfront_payment}.')

Answer 1

1. 你初始化save_amount = 0
2. 你得到annual_return 为annual_return = (save_amount * annual_return) / 12 这将是零
3. 你也会得到save_portion作为save_portion = save_portion * save_amount，这又是零
4. 因此，您在 while 循环中的 save_amount 永远不会递增，它也保持 零，save_amount < upfront_payment 始终为 true ==> 无限循环

在您的代码中

while(save_amount < upfront_payment):
   save_amount = save_amount + annual_return # 0 + 0 = 0

   # 0 + (some value * 0)/12 = 0
   save_amount = save_amount + (annual_salary - tax_portion) * save_portion / 12