简单的购物车

def register():
    username = input('请输入用户名(密码只能由数字字母组成)：').strip()
    if username.isalpha() or username.isdigit() or username.isalnum():
        with open('register', encoding='utf-8')as f1:
            for line in f1:
                uname, pwd = line.strip().split('|')
                if username == uname:
                    print('您的用户名已存在,请重新选择注册')
                    break
            else:
                while 1:
                    password = input('请输入密码(长度小于14)：')
                    if len(password)<14:
                        with open('register', encoding='utf-8', mode='a')as f2:
                            f2.write('\n{}|{}'.format(username, password))
                            print('注册成功，请继续选择登录')
                            break
                    else:
                        print('您的密码过长，请重新输入')
    else:
        print('您的输入有误，请重新选择')
def lander():
    sum = 3
    flag=True
    while flag:
        if sum == 0:
            print('对不起，您已经没有机会了,谢谢光临')
            exit()
        user_name = input('请输入您的用户名：').strip()
        with open('register', encoding='utf-8')as f1:
            for line in f1:
                uname, pwd = line.strip().split('|')
                if user_name == uname:
                    user1_password = input('请输入您的密码：').strip()
                    if user1_password == pwd:
                        print('密码正确，请继续选择购物')
                        flag=False
                        break
                    else:
                        print('密码输入有误')
                        break
            else:
                sum-=1
                print('用户名输入错误或不存在,请重新输入,您还有%s次机会'%(sum))
def shopping():
    while 1:
        money = input('请输入充值金额：').strip()
        if money.isdigit():
            money = int(money)
            print('您已成功充值%s元' % money)
            break
        else:
            print('您输入的有非数字元素，请重新输入。')
    flag = True
    while flag:
        print('有如下商品供您选择:')
        for index, commodiety_dict in enumerate(goods):
            print('{}\t{}\t{}'.format(index + 1, commodiety_dict['name'], commodiety_dict['price']))
        print('n或者N\t购物车结算\nq或者Q退出程序(如不结算购物车可直接退出)')
        select_sum = input('请输入你的选择：').strip()
        if select_sum.isdigit():
            select_sum = int(select_sum)
            if 0 < select_sum <= len(goods):
                if (select_sum - 1) not in goods_cars:
                    goods_cars[select_sum - 1] = \
                        {'name': goods[select_sum - 1]['name'], 'price': goods[select_sum - 1]['price'], 'amount': 1}
                else:
                    goods_cars[select_sum - 1]['amount'] += 1
                print('您选择的商品具体信息为：商品名称：{}\t商品价格：{}\t商品数量：1，已成功加入购物车。' \
                      .format(goods[select_sum - 1]['name'], goods[select_sum - 1]['price']))
            else:
                print('您输入的序号超出范围，请重新输入')
        elif select_sum.upper() == 'N':
                print('您购物车的具体商品如下：')
                total_price = 0
                for ind, com_dict in goods_cars.items():
                    print('序号：{}商品名称：{}商品单价：{}此商品总价：{}' \
                          .format(ind + 1, com_dict['name'], com_dict['price'], com_dict['price'] * com_dict['amount']))
                    total_price += com_dict['price'] * com_dict['amount']
                print('------->总价格为：%s元' % total_price)
                while 1:
                    if money >= total_price:
                        money -= total_price
                        print('您已经成功购买了以上商品，余额为%s元，谢谢光临~' % money)
                        flag = False
                        break
                    else:
                        print('余额不足，还差%s元' % (total_price - money))
                        choise_user=int(input('充值请按1，删除商品请按2\n请选择：'))
                        if choise_user==1:
                            money=int(input('请输入充值金额：').strip())
                        elif choise_user==2:
                            del_num = input('请输入要删除的商品序号：').strip()
                            if del_num.isdigit():
                                del_num = int(del_num)
                                if (del_num - 1) in goods_cars:
                                    goods_cars[del_num - 1]['amount'] -= 1
                                    if not goods_cars[del_num - 1]['amount']:
                                        del goods_cars[del_num - 1]
                                else:
                                    print('您输入的序号超出范围，请重新输入')
                            else:
                                print('您输入的有非数字元素，请重新输入')
        elif select_sum.upper() == 'Q':
            print('欢迎下次光临....')
            break
        else:
            print('您输入的选项不存在，请重新输入')


goods = [{"name": "电脑", "price": 1999},
         {"name": "鼠标", "price": 10},
         {"name": "游艇", "price": 20},
         {"name": "美女", "price": 998},
         ]
lst=['注册','登录','购物','退出']
goods_cars={}
while 1:
    for i in lst:
        print(lst.index(i) + 1, i)
    user_choice=int(input('请输入您的选择：').strip())
    if user_choice==1:
        register()
    elif user_choice==2:
        lander()
    elif user_choice==3:
        shopping()
    elif user_choice==4:
        print('谢谢光临，祝您生活愉快，再见！')
        break