如何使python食物计算器保持一致？

Question

while 1:
    pie = 50
    pieR = pie
    pieRem = pieR - buy
    print("We have ", pieRem, "pie(s) left!")
    buy = int(input("How many pies would you like?  "))
    pieCost = 5
    Pie = pieCost * buy
    if buy == 1:
        print(pieCost)
        pieS = pieR - buy
    elif buy > 1:
        print(Pie * 0.75)
    else:
        print("Please enter how many pies you would like!")

当我打开控制台时，它会询问我要购买多少个馅饼，而我做到了，因此，我们剩下的馅饼数量会显示出来，但是pie的值每次都会刷新。 因此，如果我第一次选择要2个饼，那就表示我们还剩48个饼（默认派值为50），然后在第二次问我之后，我输入3，而不是降到45，它会刷新下降到47。

我希望我解释得很好，希望有人知道如何解决此问题，谢谢。

Answer 1

每次您的代码循环回到开头时， pie都会重新定义为50。您需要在while循环之外定义变量pie ：

pie = 50
while 1:
    ...

---

抱歉，但是您的代码一团糟，尤其是使用变量名时。 我为您清理了：

buy = 0
pies = 50
cost = 5
while 1:
    print("We have ", pies, "pie(s) left!")
    buy = int(input("How many pies would you like?  "))   
    price = cost * buy
    if buy == 1:
        print(price)
        pies -= 1
    elif buy > 1:
        print(buy * 0.75)
        pies -= buy
    else:
        print("Please enter how many pies you would like!")

Answer 2

从下面的@Haidros代码开始

buy,pies,cost = 0,50,5
while 1:
    if pies<1:
        print ('Sorry no pies left' )
        break
    print("We have ", pies, "pie(s) left!")
    buy = int(input("How many pies would you like?  "))
    if pies-buy<0:buy = int(input("Only %s pies remaining How many pies would you like?"%pies))                  
    if buy>0:
        if buy==1:print(cost*buy)
        else:print(cost*buy * 0.75)
        pies-=buy       
    else:
        print("Please enter how many pies you would like!")

Answer 3

如果使用类和对象，则无需使用全局变量，并且可以轻松地将代码扩展到其他产品（例如：羊角面包，百吉饼，汤，咖啡，三明治或其他。）

class pies:
""" Object To Sell Pies """

def __init__(self):
    """ Constructor And Initialise Attributes """       
    self.pies=50
    self.amount = 0     
    self.cost = 5

def buy(self,buy):
    """ Method To Buy Pies """       

    if (buy > self.pies):
        print "Sorry Only %d Pies in Stock" % self.pies
    elif (self.pies >= 1):
        self.pies =self.pies - buy
        print "Cost is : %.02f" % ( 0.75 * buy )
        print "We have %d and pies in stock" % (self.pies) 
    elif (self.pies == 1):
        self.pies =self.pies - buy
        print "Cost is : %.02f" % ( self.cost * buy )
        print "We have %d pies in stock now" % (self.pies) 

    else:
        print "Sorry Pies Out of Stock !"  
        self.buy = 0
        self.pies = 0

将上面的代码另存为pieobject.py，然后使用以下代码进行调用：

#!/usr/bin/env python

import os
from pieobject import pies

p = pies()

while True:

    try:
        amount=int(raw_input('Enter number of pies to buy:'))
    except ValueError:
        print "Not a number"       
        break

    os.system('clear')  
    p.buy(amount)