购物车程序

                                                         项目名称：购物车程序
项目要求：
1.要求输入用户的工资，然后打印购物的菜单
2.用户可以不断的购买商品直到钱不够为止
3.退出时格式化用户已购买商品和所剩的余额
　　

　　对于此项目我主要利用了字典的优点。
程序流程图：

项目代码：

#encoding=utf-8
__author__ = 'heng'
"""
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项目名称：购物车程序
项目要求：
1.要求输入用户的工资，然后打印购物的菜单
2.用户可以不断的购买商品直到钱不够为止
3.退出时格式化用户已购买商品和所剩的余额

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"""
import sys
#购物车，用于存放购买成功的商品
shopping_cart = {}
#打印商品的种类和价格
the_goods = {'bike':999,
             'milk':80,
             'car':19999,
             'iphone':5000,
             'ipad':3000,
             'ituch':1000,
             'iwatch':400,
             'macbook':9000
}
print 'the goods and price :'
#将字典中的信息全部打印出来
for i in the_goods:
    print i,':',the_goods[i]
the_money = float(raw_input('please enter your money:'))
the_priece = 0  #用来统计购买商品的数量
while True:
    print 'You can buy:'
    i = 0
#判断可以支付的商品种类
    for j in the_goods:
        if the_goods[j] <= the_money:
            i+=1
            print j,':',the_goods[j]
    if i==0:
        print "You don't have enough money,you can buy nothing!go home man!"
#用户是否继续购物
    if_leave = raw_input("DO you want to buy continue?y/n")
    if if_leave == 'y':
        want_buy = raw_input("please enter the goods you want to buy:")
        #判断输入的是否正确
        if want_buy not in the_goods.keys():
            print "the goods can't find!"
        else:
            if the_goods[want_buy] <= the_money:       #判断用户是否可以支付
                if want_buy in shopping_cart:          #用来计算购买的数量
                    shopping_cart[want_buy][1]+=1
                else:
                      shopping_cart[want_buy] = [the_goods[want_buy],1]
                the_money = the_money - the_goods[want_buy]
                print "you buy %s succeed!"%want_buy
            else:
                print "the good is too expensive for you ,you don't have enough money !"

            print "your balance is : %.2f"%the_money
    else:
        print "you had buy:"
        for k in shopping_cart:     #输出购物车中的物品和数量
            print shopping_cart[k][1],'piece ',k
        print "your balance is : %.2f"%the_money
        sys.exit()