今天写着购物车的作业,最头疼的是文件操作了
尤其是文件的打开模式 w r a 最TM的头疼
r+模式可读可写,但是写的内容会根据文件指针去覆盖之前的内容,当文件需要修改时,强烈建议不要用这种模式,会有一个坑
下面说说文件的思路吧,还没有学习函数,因此代码起来很乱
1.设置接口
#user接口
if ident_flag == ‘u‘:
首先读入文件的数据
#
商品信息
with open("goods.txt",‘r‘) as goods_file:
goods_info = {}
for line in goods_file.readlines():
item = line.strip(‘n‘).split(‘‘)
goods_info[item[0]] = item[1]
# 余额信息
with open("balance.txt",‘r‘) as balance_file:
balance = int( balance_file.readline().strip(‘n‘) )
购买商品
#
购买商品
buy_name = input("Which goods would your like to buy?(input the name of goods)>>: ")
if buy_name in goods_info:
if balance > int( goods_info[buy_name] ):
balance = balance - int( goods_info[buy_name] )
shopping_list[buy_name] = goods_info[buy_name]
else:
print("I‘m sorry to hear that you have not enough money to buy this")
else:
print("Sorry sir, there is not the goods that you need!!n")
结账
#
结算
with open("balance.txt",‘w‘) as goods_file:
goods_file.write(str(balance))
#manager接口
elif ident_flag == ‘m‘:
首先读入文件
#
商品信息
with open("goods.txt",‘r‘) as goods_file:
goods_info = {}
for line in goods_file.readlines():
item = line.strip(‘n‘).split(‘‘)
goods_info[item[0]] = item[1]
增加商品
#
增加商品
if choice == ‘a‘:
print("you are adding a goods".center(50,‘-‘))
goods_name = input("The goods_name is: ")
goods_price = input("The goods_price is: ")
print("n".rjust(51,‘-‘))
info = goods_name + ‘‘ + goods_price + ‘n‘
with open("goods.txt", ‘a‘) as goods_file:
goods_file.write(info)
修改商品
#
修改商品
elif choice == ‘m‘:
print("You are modify a goods".center(50, ‘-‘))
goods_name = input("The goods_name is: ")
if goods_name in goods_info:
goods_price = input("The goods_price is: ")
goods_info[goods_name] = goods_price
with open("goods.txt", ‘w+‘) as goods_file:
for item in goods_info:
info = item + ‘‘ + goods_info[item] + ‘n‘
goods_file.write(info)
else:
print("Sorry sir, there is not -{_goods_name}-!".format(_goods_name = goods_name))
删除商品
#
删除商品
elif choice == ‘d‘:
print("you are delete a goods".center(50, ‘-‘))
goods_name = input("The goods_name is: ")
if goods_name in goods_info:
goods_info.pop(goods_name)
with open("goods.txt",‘w‘):
for item in goods_info:
info = item + ‘‘ + goods_info[item] + ‘n‘
goods_file.write(info)
原文：http://www.cnblogs.com/JackyPeng/p/6883666.html
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