一个购物车实例，大量的列表，字典，文件互相写入，读取操作。

对于嵌套字典的取值，比较繁琐。

该程序功能较为单一，代码了较大，没有使用函数，有很多地方可以改进。

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    
    import os,sys,time
    
    # init menu prod list
    _prod_list = []
    
    # init a shopping cart
    _shopping_his = []
    _shopping_cart = []
    
    # init user info list
    _user = {}
    
    # load prod list
    if not os.path.exists("w2_prod.txt"):
        open("w2_prod.txt", "w").close()
    else:
        with open("w2_prod.txt","r") as prod_list:
            lines = prod_list.readlines()
            if lines:
                print("Load prod list...")
                for line in lines:
                    _prod_list.append(line.strip())
            else:
                print("Nothing in prod list. Please import production with the format: prod_name,prod_price")
                exit()
    
    # create user list and buy list
    if not os.path.exists("w2_user.txt"):
        open("w2_user.txt","w").close()
    if not os.path.exists("w2_buy.txt"):
        open("w2_buy.txt","w").close()
    
    
    # init user info
    with open("w2_user.txt","r+") as names:
        lines = names.readlines()
        if lines:
            print("Load user information...")
            for i in range(len(lines)):
                _user[str(i)] = {}
                (_id,_uname,_upwd,_ustate,_ubalance) = lines[i].strip().split(",",5)
                _user[str(i)]["name"] = _uname
                _user[str(i)]["password"] = _upwd
                _user[str(i)]["state"] = _ustate
                _user[str(i)]["balance"] = int(_ubalance)
        else:
            print("It is empty")
            print("Hello, it is your first time to access....")
            print("Please enter your information:")
            _name = input("Name:")
            _pwd = input("Password:")
            _state = ‘enable‘
            _salary = int(input("Salary:"))
            _uid = str(len(_user))
            names.write("%s,%s,%s,%s,%d" %(_uid,_name,_pwd,_state,_salary))
            #load user info
            _user[_uid] = {}
            _user[_uid]["name"] = _name
            _user[_uid]["password"] = _pwd
            _user[_uid]["state"] = _state
            _user[_uid]["balance"] = _salary
    
    #login system and user identity authentication
    print("Login".center(30,"="))
    _name = input("Name:")
    with open("w2_user.txt", "r") as users:
        lines = users.readlines()
        for i in range(len(lines)):
            if _name == _user[str(i)]["name"]:
                _pwd = input("password:")
                if _pwd == _user[str(i)]["password"]:
                    print("Welcome to login !")
                else:
                    print("The password is error...")
                    exit()
            else:
                print("The user is not exist.")
                exit()
    
    #load shopping cart
    with open("w2_buy.txt","r") as buy_lists:
        lines =  buy_lists.readlines()
        if lines:
            print("\033[1;37;44m Shopping_History \033[0m ".center(30,"="))
            for i in lines:
                _shopping_his.append(i.strip())
            print("\033[1;37;44m",_shopping_his,"\033[0m")
        else:
            print("Nothing in shopping cart".center(40,"="))
    
    #load balance
    _balance = []
    for i in _user.keys():
        balance = int(_user[i]["balance"])
        _balance.append(balance)
    print("\033[1;31m Balance:",_balance,"\033[0m")
    balance = int(_balance[0])
    
    while True:
        # load prod list
        print("The Production List".center(30,"="))
        for index, menu_list in enumerate(_prod_list):
            print(index, menu_list)

    #user operation
    _select1 = input("Your selection[History:h|Recharge:r|Quit:q]:")
    if _select1.isdigit():
        _select1 = int(_select1)
        if _select1 > -1 and _select1 <= len(_prod_list):
            (pname,pprice) = str(_prod_list[_select1]).strip().split(",")
            pprice = int(pprice)
            for i in _user.keys():
                balance = _user[str(i)]["balance"]
                print(balance)
                print(pprice)
                if balance >= pprice:
                    balance -= pprice
                    print("\033[1;34m Add %s to shopping cart. \033[0m" %pname)
                    _shopping_cart.append(pname)
                    print("\033[1;35m Shopping_Cart:",_shopping_cart,"\033[0m")
                    print("Shopping His:",_shopping_his)
                    print("\033[1;31m Balance RMB:",balance,"\033[0m")
                    for i in _user.keys():
                        _user[i]["balance"] = balance
                else:
                    print("\033[1;31m Balance is not enough.\033[0m")
                    continue
        else:
            print("\033[1;31m It is out of range! \033[0m")
    elif _select1 == "q":
        print("\033[1;35m Total:", _shopping_cart, "\033[0m")
        print("Saving summary report of \033[1;31m w2_report.txt \033[0m ...")
        for i in range(20):
            sys.stdout.write("#")
            sys.stdout.flush()
        time.sleep(0.2)
        #build report
        shopping = _shopping_cart+_shopping_his
        item = set(shopping)
        with open("w2_report.txt","w") as report:
            for i in item:
                print(i,shopping.count(i),file=report)
        #update user info
        for i in _user.keys():
            _quid = i
            _qname = _user[str(i)]["name"]
            _qpassword = _user[str(i)]["password"]
            _qstate = _user[str(i)]["state"]
            _qbalance = _user[str(i)]["balance"]
            with open("w2_user.txt","w+") as names:
                names.write("%s,%s,%s,%s,%d" %(_quid,_qname,_qpassword,_qstate,_qbalance) )
        #store prod in file
        with open("w2_buy.txt","a") as saves:
            for i in _shopping_cart:
                print(i,file=saves)
        exit()
    elif _select1 == "h":
        print("\033[1;37;44m You had got items before:",_shopping_his,"\033[0m")
    elif _select1 == "r":
        _money = input("How much cash do you want to add:")
        if _money.isdigit():
            _money = int(_money)
            for i in _user.keys():
                _user[str(i)]["balance"] = int(_user[str(i)]["balance"]) + _money
                print(_user[str(i)]["balance"])
                break
        else:
            print("\033[1;31m It is not a digit! \033[0m")
            continue
    else:
        print("\033[1;31m It is not a digit! \033[0m")

本文出自 “Clark的运维” 博客，谢绝转载！

Python-w2