尝试打开和读取二进制文件时如何解决EOF错误 [英] How to solve an EOF error when trying to open and read a binary file

问题描述

我正在学习读写二进制文件，并从一本书中复制代码以说明如何完成此工作。我整理了本书中的两段代码以完成此任务。在编译我的代码时，出现EOF错误，并且不确定是什么原因引起的。你能帮我吗？我正在编写的代码在下面列出。

I am learning to write and read from a binary file and am copying code out of a book to illustrates how this is done. I have put together two pieces of code from the book to complete this task. On compilation of my code I get an EOF error and am not sure what is causing it. Can you help? The code I am writing is listed below.

class CarRecord:                    # declaring a class without other methods
    def init (self):                # constructor
        self .VehicleID = ""
        self.Registration = ""
        self.DateOfRegistration = None
        self.EngineSize = 0
        self.PurchasePrice = 0.00

import pickle                       # this library is required to create binary f iles
ThisCar = CarRecord()
Car = [ThisCar for i in range (100)]

CarFile = open ('Cars.DAT', 'wb')   # open file for binary write

for i in range (100) :              # loop for each array element
    pickle.dump (Car[i], CarFile)   # write a whole record to the binary file

CarFile.close() # close file

CarFile = open( 'Cars.DAT','rb')    # open file for binary read
Car = []                            # start with empty list
while True:                         # check for end of file
    Car.append(pickle.load(CarFile))# append record from file to end of l i st

CarFile.close()

推荐答案

您正在无限循环地从文件中读取汽车：

You are reading cars from the file in an infinite loop:

while True:                         # check for end of file
    Car.append(pickle.load(CarFile))# append record from file to end of l i st

在文件末尾，这将正确引发EOF异常。有两种方法可以解决此问题：

At the end of the file, this will correctly throw an EOF exception. There are two ways to handle this:

1. 不是将其加载为无限循环，而是将整个数组写为pickle，然后重新加载：

1. Instead of loading in an infinite loop, write the whole array as a pickle, then load it back:

CarFile = open ('Cars.DAT', 'wb')   # open file for binary write
pickle.dump(Car, CarFile)           # write the whole list to a binary file
...
CarFile = open('Cars.DAT', 'rb')    # open file for binary read
Car = pickle.load(CarFile)          # load whole list from file

捕获异常，然后继续。这种样式称为 EAFP 。

Car = []                            # start with empty list
while True:                         # check for end of file
    try:
       Car.append(pickle.load(CarFile)) # append record from file to end of list
    except EOFError:
        break                       # break out of loop

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