Python implementiert das Einkaufswagen-Einkaufs-Applet

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
@author: 烽火
@license: Apache Licence
@file: shopping.py
@time: 6/16/17 10:05 AM
"""

goods = [
  ("IPhone", 5800),
  ("Watch", 2000),
  ("MacBook", 12000)]

goods_cart = []

mybudget = input("请输入您的预算:")

# 不考虑是小数的情况
while not mybudget.isdigit():
  mybudget = input("输入有误,请重新输入您的预算:")
mybudget = int(mybudget);

while True:
  print("商品列表".center(50, "-"))
  print("编号".center(8, " "), "名称".ljust(30, " "), "价格".ljust(10, " "))
  for i in enumerate(goods):
    print(str(i[0]).center(10, " "), str(i[1][0]).ljust(31, " "), str(i[1][1]).ljust(10, " "))

  user_choose = input("请输入您的选择:")

  if user_choose.isdigit():
    user_choose = int(user_choose)
    if user_choose >= 0 and user_choose < len(goods):
      if (mybudget - goods[user_choose][1]) >= 0:
        goods_cart.append(goods[user_choose])
        mybudget -= goods[user_choose][1]
        print("预算还有%d" % mybudget)
      else:
        print("预算不够啦~")
    else:
      print("不存在该商品~")

  elif user_choose == &#39;q&#39;:
    break

  else:
    print("您的输入有误~")

print("预算还剩%d了" %(mybudget))
print("购物车商品信息".center(50, "-"))

for i in enumerate(goods_cart):
    print(str(i[0]).center(10, " "), str(i[1][0]).ljust(31, " "), str(i[1][1]).ljust(10, " "))