AttributeError:“NoneType”对象在python中没有“读取”属性。

if __name__ == '__main__':
    filename = open('sevi.txt', 'wb')
    content = filename.write("Cats are smarter than dogs")
    for line in content.read(): 
        match = re.findall('[A-Z]+', line)
        print match
    filename.close()

I am new to python. I am just opening a file and writing some text into it. Later reading the content find all the characters in it by using regular expression. but I am getting the error as 'NoneType' object has no attribute 'read'. if I use readlines also, I am getting the error.

我是python的新手。我只是打开一个文件，然后写一些文本进去。之后，通过使用正则表达式来读取内容，找到其中的所有字符。但我将错误理解为'NoneType'对象没有属性'read'。如果我使用readlines，我也会得到错误。

3 个解决方案

#1

The file.write() method returns None in Python 2 (in Python 3 it returns the number of bytes written, for a binary file).

write()方法在python2中没有返回(在python3中，它返回所写的二进制文件的字节数)。

If you want to both write and read with the same file you'll need to open that file in w+ mode, and seek back to put the file position back to the start:

如果你想用相同的文件来写和读，你需要在w+模式下打开这个文件，然后返回到开始的文件位置:

with open('sevi.txt', 'w+b') as fileobj:
    fileobj.write("Cats are smarter than dogs")
    fileobj.seek(0)  # move back to the start
    for line in fileobj: 
        match = re.findall('[A-Z]+', line)
        print match

Note that looping over the file object can be done directly, producing individual lines.

注意，对文件对象的循环可以直接完成，生成单独的行。

I made two other changes: I renamed your variable to fileobj; you have a file object, not just the name of the file here. And I used the file object as a context manager, so that it is closed automatically even if any errors occur in the block.

我还做了另外两个更改:我将变量重命名为fileobj;您有一个文件对象，而不仅仅是文件的名称。我使用file对象作为上下文管理器，因此即使在块中出现任何错误，它也会自动关闭。

#2

filename.write("Cats are smarter than dogs") is the function that returns None type like every function in Python if it's not specified otherwise with a return statement. So the value of the variable content is None and You are trying to read from that. Try filename.read() instead.

文件名。write(“猫比狗更聪明”)是一个函数，如果没有指定返回语句，它返回的函数不会像Python中的每个函数一样。所以变量内容的值是None，你要从中读取。尝试filename.read()。

#3

import re 

ofile = open('sevi.txt', 'r+')

ofile.write("Cats are smarter than dogs")

ofile.seek(0)

data = ofile.read()

upper = re.findall(r'[A-Z]', data)

print upper

lower = re.findall(r'[a-z]', data)

print lower

ofile.close()

#1