从（可能为空）文件中删除

Question

所以我试图创建一个文件并从中读取，即使它是空的。因此，下次运行程序时，文件已经存在，并且其中将有数据。

#this should create the file
filename = open("roombooking.bin","wb")
#this should load the data into a list but since its first created it should be an empty list
monday=pickle.load(open("roombooking.bin","rb"))

这是我得到的错误

Traceback (most recent call last):
    monday=pickle.load(open("roombooking.bin","rb"))
  File "C:\Python27\lib\pickle.py", line 1378, in load
    return Unpickler(file).load()
  File "C:\Python27\lib\pickle.py", line 858, in load
    dispatch[key](self)
  File "C:\Python27\lib\pickle.py", line 880, in load_eof
    raise EOFError
EOFError

Answer 1

pickle不起作用：空文件不会创建空列表。

一个空列表在pickle文件中看起来像这样：

(lp0
.

如果您想处理它以便空文件导致空列表，您可以使用try / except块：

try:
    monday=pickle.load(open("roombooking.bin","rb"))
except EOFError:
    monday = []

请注意，“下次运行程序时”，如果行filename = open("roombooking.bin","wb")发生，它将覆盖文件。