购物车小程序

第一版：

salary = input('请输入您的总额：')
if salary.isdigit():
    salary = int(salary)
else:
    quit('总额仅支持输入数字')

list = []
list1=['iphoneX','mac_book','iphone8','python_book']
list2 = [7800,10000,7000,90]

msg = '''
------购物车菜单如下：----------
0.Iphone X:%d
1.Mac Book:%d
2.Iphone 8:%d
3.Pythone Book:%d
4.退出
------------------------------
''' % (list2[0],list2[1],list2[2],list2[3])

print(msg)

n=input('>>>>>>>>>>>')
if n.isdigit():
    n = int(n)
else:
    quit('仅能输入0-4')

while n>-1 and n<4:
    if salary-list2[n] < 0:
        print('您当前余额不足请及时充值')
        break
    else:
        msg1='''
        您当前购买的%s，已加入到购物车。
        当前余额为：%d
        ''' % (list1[n],salary-list2[n])
        print(msg1)
        list.append(list1[n]) #把每次购买的商品添加到空数组
        salary = salary-list2[n]
        n = input('>>>>>>>>>>>>>>')

        if n.isdigit():
            n=int(n)
        else:
            print('仅能输入0-4')
            break

#输出购物车商品
print('您加入购物车的商品如下：')
a = len(list)
b = 0
while b<a:
    print(list[b])
    b = b + 1

print('您当前余额为：',salary)

优化后

product_list = [
    ('Mac',9000),
    ('kindle',800),
    ('tesla',900000),
    ('python book',105),
    ('bike',2000),
]


saving = input('please input your saving:')
shopping_car=[]
#判断输入saving是否合法
if saving.isdigit():
    saving = int(saving)

    while True:

        #输出商品列表
        # for i in product_list:
        for i,v in enumerate(product_list,1):
            print(i,v[0],v[1])
        #     print(product_list.index(i),i[0],':',i[1])


        choice=input('选择购买的是那个品编号【退出：q】')
        #判断输入的商品序号是否合法
        if choice.isdigit():
            choice = int(choice)
            #判断输入的商品序号是否在数组中
            if choice>0 and choice<len(product_list):
                #把选择的商品赋值给新数组
                p_item=product_list[choice-1]
                #判断选择的商品价格是否小于输入的总金额
                if p_item[1]<saving:
                    #算出剩余的金额
                    saving=saving-p_item[1]
                    #把购买的商品赋值给新数组
                    shopping_car.append(p_item)

                else:
                    print('余额不足，还剩%s'% saving)
                    print('您购买的商品如下')
                    for i in shopping_car:
                        print(i)
                    quit()
            else:
                print('编码不存在')
        elif choice=='q':
            print('您购买的商品如下')
            for i in shopping_car:
                print(i)
            print('您还剩%s元钱'%saving)
            break
        else:
            print('invalid input')
else:
    print('请输入正整数')