模擬購物車的程序，是對之前學習的基礎知識----字典、列表、文件的讀寫、字符的操作等知識的一次模擬練習，但在實際的編程中，將所有功能放在一個函數中實現，無疑減弱了程序的可讀性和可維護性，購物車4引進了函數的概念，也將購物車需求經過整理如下：

要求

1、 登錄功能

1> 登錄驗證：1、賬戶是否被鎖定；2、驗證用戶為註冊用戶，登錄密碼是否正確，用戶名與密碼存放在文件中；

2> 驗證失敗三次，鎖定賬戶，鎖定賬戶在五分鐘內不能再次登錄，鎖定賬：

戶存放在文件中。

2、 賬戶充值

1> 在購物時，出現余額不足是，可進行賬戶充值；

2> 可讀取、保存賬戶余額。

3、 退出結算

1> 結束購物時，進行購物結算，打印消費信息與賬戶余額；

2> 購物結束時，保存購物商品信息；

3> 購物結束時，保存賬戶余額。

4、 購物

1> 打印操作說明；

2> 打印商品列表；

3> 商品分類；

4> 余額不足提示。

5> 購物操作，可根據不同購物類型，選擇，顯示該類型下商品列表，可選擇返回上層目錄。

實現代碼如下：

def readDirInfo(filename):
    ‘讀取字典列表，依據傳遞的文件名，獲取不同的字典信息‘
    nameList = ‘‘
    with open(filename, 
 
‘a+‘, encoding=‘utf8‘) as f:
        f.seek(0)
        nameList = str(f.readlines())

    nameList = nameList.strip(‘]‘).strip(‘[‘)
    nameList = nameList.strip(‘\"‘).strip(‘\"‘)

    if len(nameList) == 0:
        return {}

    return eval(nameList)    #字符轉字典

def login(iTime = 3):
    ‘用戶登錄操作,包括以下功能:1、判斷是否為註冊賬戶；    2、登錄賬戶是否被鎖定(註：默認輸錯用戶名密碼三次後，鎖定賬號,五分鐘內不能登錄)
 
‘
    i = 1
    flag = False

    lock_namelist = readDirInfo(‘locklist.txt‘)
    while i <= iTime:
        username = input("username:")
        password = input("password:")

        if loginLock(username,lock_namelist):
            print("you username is locked, try again after 5 min")
            break
        elif logincheck(username,password):
            print("welecom to shopping maket")
            flag = True
            break
        elif i == iTime:
            print("input more than three times, try again after 5 min")
            addLockDir(username, lock_namelist)
            break
        else:
            print("you put an wrong name or password,please input again")

        i += 1
    return flag,username

def loginLock(name, lock_namelist):
    ‘判斷登錄賬號是否被鎖定，如果被鎖定時間超過5分鐘，允許用戶再次登錄‘
    flag = False

    if name in lock_namelist:
        last_time = datetime.datetime.strptime(lock_namelist[name], "%Y-%m-%d %H:%M:%S")
        now_time = datetime.datetime.now()
        minute = (now_time - last_time)
        if int(minute.seconds/60) <= 5:
            flag = True

    return flag

def logincheck(name,password):
    ‘是否為註冊賬號‘
    flag = False
    name_dir = readDirInfo(‘name.txt‘)

    if name in name_dir:
        if password == name_dir[name]:
            flag = True

    return flag

def addLockDir(name,lock_namelist):
    ‘字典中添加元素，如果元素存在，修改元素的值‘
    if name in lock_namelist:
        lock_namelist[name] = datetime.datetime.now().strftime( "%Y-%m-%d %H:%M:%S")
    else:
        lock_namelist[name] = datetime.datetime.now().strftime( "%Y-%m-%d %H:%M:%S")

    with open(‘locklist.txt‘, ‘w‘, encoding="utf8") as f_read:
        f_read.write(str(lock_namelist))

def PrintOper():
    ‘打印操作說明‘
    prolist = ‘‘‘
    ***************   系統操作說明   ****************
       q : 退出系統
       c : 賬號充值
       h : 購物記錄
       l : 商品列表
    ************************************************
    ‘‘‘
    print(prolist)

def CreateDir():
    ‘判斷文件夾是否存在，如果存在則退出，如果不存在，創建文件夾‘
    isExists = os.path.exists(‘History‘)

    if not isExists:
        os.mkdir(‘History‘)

    return isExists

def Exit():
    ‘退出購物系統,退出時進行購物結算‘
    Account()
    saveLevelMoney()
    exit()

def saveLevelMoney():
    with open(‘remain.txt‘,‘w‘,encoding=‘utf8‘) as f:
        f.write(str(remain_dir))

def Account():
    ‘購物計算，將購物信息寫入購物歷史文件中‘
    if len(shopping_cart) == 0:
        return False

    print("\033[34;1m---------------product list-----------------\033[0m \n \033[42;1m")
    temp = ‘id   product       number pric Totalpric‘
    print(temp)
    index = 1
    total_mon = 0

    f = open("product.txt", "a+", encoding="utf8")
    now_time = datetime.datetime.now().strftime(‘[%Y-%m-%d %H:%M:%S]‘)
    f.write(now_time + ‘\n‘ + temp + ‘\n‘)

    temp = ‘‘
    for i in shopping_cart.keys():
        total_mon += shopping_cart[i][1] * shopping_cart[i][0]
        temp = str("%d %10s %7d %7d %7d \n" % (index, i, shopping_cart[i][1], shopping_cart[i][0],
                                       shopping_cart[i][1] * shopping_cart[i][0]))

        print(temp)
        f.write(temp)
        index += 1

    f.close()

    print("you pay money is:%d \n you level money is: %d \n" % (total_mon, remain_dir[name]))
    print("\033[0m \n \033[34;1m-------------end-------------\033[0m")

def  Recharge():
    ‘賬號充值操作‘
    while True:
        temp = input("Please rechange money:")

        if temp.isdigit():
            if name in remain_dir:
                remain_dir[name] += int(temp)
            else:
                remain_dir[name] = int(temp)
            break

        print("you input a unknow number,please check it and input again!")

def History():
    ‘打印歷史購物記錄‘
    filename = ‘History\\‘ + name + ‘.txt‘
    filename = filename.rstrip("\\")

    print(filename)
    if os.path.exists(filename):
        with open(filename,‘r‘,encoding=‘utf8‘) as f:
            for line in f:
                print(line.strip(‘\n‘))

    else:
        print(‘No you shoppong history‘)

def Operation():
    ‘用戶交互操作‘
    while True:
        PrintOper()
        oper = str(input("Please input you choice:")).strip()

        if oper == ‘l‘:
            print(‘歡迎進入購物中心‘)
            shopping(product_list)
        elif oper in Oper_dir:
            Oper_dir[oper]()
        else:
            print("You input no in Oper list!")
            continue

def ProductList(print_list):
    ‘打印商品列表‘
    if isinstance(print_list, dict):  # 是否為列表
        for key in print_list:
            print(key)
    else:
        index = 0
        for product in print_list:
            print(index, product)
            index += 1

        print(‘b:‘,‘返回上級菜單‘)

    print(‘q:‘,‘退出購物中心‘)
    print(‘c‘,‘充值‘)

def shopping(product_list):
    ‘購物操作‘
    current_layer = product_list
    while True:
        ProductList(current_layer)
        choice = input(">>:").strip()
        if len(choice) == 0: continue

        if choice.isdigit():
            choice = int(choice)
            if choice >= 0 and choice < len(current_layer):
                product = current_layer[choice]
                if product[1] <= remain_dir[name]:
                    if product[0] in shopping_cart:
                        shopping_cart[product[0]][1] += 1
                    else:
                        shopping_cart[product[0]] = [product[1], 1]
                    remain_dir[name] -= product[1]
                    print("\033[42;1mAdded product: %s  into shoing cart ,you current balance %s \033[0m"
                          % (product[0], str(remain_dir[name])))
                else:
                    print("\033[42;1m [warning] you balance is no enough\033[0m, product:" + str(
                        product[1]) + " short for " + str(product[1] - remain_dir[name]))
            else:
                print("\033[41;1mYou choice product is no in product_list\033[0m")

        elif choice in current_layer:
            if isinstance(current_layer, dict):  # 是否為列表
                last_layer.append(current_layer)
                current_layer = current_layer[choice]
        elif choice == ‘q‘:
            break
        elif choice == ‘b‘:
            current_layer = BackUpLevel(current_layer)
        elif choice == ‘c‘:
            Recharge(name)

def BackUpLevel(current_layer):
    ‘返回到商品列表上一層‘
    if last_layer:
        current_layer = last_layer[-1]
        last_layer.pop()

    return  current_layer

import datetime
import os

product_list = {"生活用品":[[‘毛巾‘,20],
                [‘洗衣液‘,80],
                [‘衣架‘, 10],
                [‘洗衣粉‘,60],
                [‘洗發水‘, 80],
                [‘廁洗劑‘,50]],
                "家電":[[‘電視機‘,5000],
                      [‘電飯煲‘,300],
                      [‘電磁爐‘,200],
                      [‘高壓鍋‘,800],
                      [‘電餅鐺‘,200]],
                }

shopping_cart = {}
Oper_dir = {‘q‘:Exit,‘c‘:Recharge,‘h‘:History}
last_layer = [ product_list ]
remain_dir = readDirInfo(‘remain.txt‘)
flag,name = login()

if flag:
    Operation()

python學習--購物車4