ATM案例

##### Author:yyw, created on 20180509 #####
'''
0. Define functions
    - prt_all_prod(prod_dict)
    - get_price_by_index(prod_dict, _index)
    - get_sku_by_index
    - valid_cus_name
    - get_balance_by_name
    - upd_balance_by_name(filename,name,balance)
1. Get customer name;
2. Print shopping list;
3. Loop: input index and get price summary, break by press 'q';
4. Write shopping transaction to transaction file, and update balance in balance file
'''
import json
import time

def prt_all_prod(prod_dict):
    for index,i in enumerate(prod_dict):
        print(index,i,prod_dict[i])
    return

def get_price_by_index(prod_dict, _index):
    for index,i in enumerate(prod_dict):
        while index ==_index:
            _price = prod_dict[i]
            break
    return _price

def get_sku_by_index(prod_dict, _index):
    for index,i in enumerate(prod_dict):
        while index ==_index:
            _sku = i
            break
    return _sku

def valid_cus_name(name_list,cus_name):
    result = name_list.get(cus_name, "NO")
    return result

def get_balance_by_name(name_list,_cus_name):
    balance = name_list.get(_cus_name)
    return balance

def upd_balance_by_name(filename, _name,balance):
    with open(filename, "r") as fr:
        info2 = json.loads(fr.read())
        info2[_name] = balance
       # print(info2)
    with  open(filename, "w") as f:
        f.write(json.dumps(info2))
    return 0

### 1.Print shopping list;
with  open("sku","r") as f:
    sku_list = json.loads(f.read())
    #print(data)


### 2. Get customer name;
print("------开始校验姓名------")
with  open("balance","r") as f:
    name_list = json.loads(f.read())
    print(name_list)

_name = input("请输入您的姓名》》》：")
while valid_cus_name(name_list,_name) =="NO" :
    _name = input("输入的姓名不是金卡会员，请再次输入您的姓名》》》：")
    if _name == 'q':
        print("@@@@用户要求退出程序！！！")
        break

_bal = get_balance_by_name(name_list,_name)
print("
##### 欢迎 %s 来到星空购物广场 #####
"%_name)
print("
##### 您的账号余额还有 %s 元，不过您可以透支消费，#####
"%_bal)

print("-------------商品列表-------------")
prt_all_prod(sku_list)
#print(get_sku_by_index(sku_list,0))
#print(get_price_by_index(sku_list,0))
_shopping_cart =[]
_summary = 0
_count = 0
_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
while True:
    _choice = input("请输入您想购买的商品编号，或者按 'q' 退出》》》:")
    if _choice.isdigit():
        _choice = int(_choice)
        if _choice < len(sku_list) and _choice >= 0:  # 判读list范围
            p_price = get_price_by_index(sku_list,_choice)
            p_sku = get_sku_by_index(sku_list,_choice)
            ### 添加记录到shop，列表
            _shopping_cart.append([p_sku,p_price])
            _summary = _summary+p_price
            _count = _count+1
            print("加入 33[31;1m%s33[0m 到购物车! 花了 33[31;1m%s33[0m 元, 总计消费了 33[31;1m%s33[0m 元" %(p_sku,p_price,_summary))
        else:
            print("商品 %s 不存在！！" % (_choice))
    elif _choice == 'q':
        with open("shopping_trx", "a", encoding="UTF-8") as f_trx:
            print("
------shopping list---------")
            for p in _shopping_cart:
                f_trx.writelines(_time+" "+_name+" "+p[0]+" "+str(p[1])+"
") ####list如果转化为str
                print(p)
        print("33[31;1m%s33[0m购物完成，总计购买了 33[31;1m%s33[0m 件商品，花了 33[31;1m%s33[0m 元，祝您购物愉快!"%(_name,_count,_summary))
        ### 将本次交易总计写入账户
        with open("account_trx", "a", encoding="UTF-8") as acc_trx:
            acc_trx.writelines(_time+" "+_name+" "+str(0-_summary)+"
")
        
        ### 更新客户账户信息
        _balance  =_bal-_summary
        #print(str(_balance))
        upd_balance_by_name("balance",_name,_balance)
        if _balance >= 0 :
            print("33[31;1m%s33[0m，您的账户为 33[31;1m%s33[0m 元，希望您再次光临!" % (_name, _balance))
        else:
            print("33[31;1m%s33[0m，您的账户余额已经不够，需要还款金额为 33[32;1m%s33[0m 元，不过不用担心，可以找你爸爸!"%(_name,_balance))
        exit()
    else:
        print("Invalid number!")
        break  # 注意break的位置

其中文件没有设置变量，直接常量写进去了