TypeError：在Python3中写入文件时需要一个类似字节的对象，而不是'str' [英] TypeError: a bytes-like object is required, not 'str' when writing to a file in Python3

问题描述

我最近已迁移到Py 3.5。
此代码在Python 2.7中正常工作：

I've very recently migrated to Py 3.5. This code was working properly in Python 2.7:

with open(fname, 'rb') as f:
    lines = [x.strip() for x in f.readlines()]

for line in lines:
    tmp = line.strip().lower()
    if 'some-pattern' in tmp: continue
    # ... code

升级到3.5之后，我得到了：

After upgrading to 3.5, I'm getting the:

TypeError: a bytes-like object is required, not 'str'

最后一行错误（模式搜索代码）。

error on the last line (the pattern search code).

我尝试在语句的任何一侧使用 .decode（）函数，也尝试过：

I've tried using the .decode() function on either side of the statement, also tried:

if tmp.find('some-pattern') != -1: continue

-无济于事。

我能够迅速解决几乎所有的2：3问题，但是这个小问题困扰着我。

I was able to resolve almost all 2:3 issues quickly, but this little statement is bugging me.

推荐答案

您以二进制模式打开文件：

You opened the file in binary mode:

with open(fname, 'rb') as f:

这意味着从文件读取的所有数据均以<$返回c $ c> bytes 个对象，而不是 str 个对象。然后，您不能在遏制性测试中使用字符串：

This means that all data read from the file is returned as bytes objects, not str. You cannot then use a string in a containment test:

if 'some-pattern' in tmp: continue

您必须使用 bytes 对象对 tmp 代替：

You'd have to use a bytes object to test against tmp instead:

if b'some-pattern' in tmp: continue

或以文本文件形式打开文件，而不是替换'rb'模式，并带有'r'。

or open the file as a textfile instead by replacing the 'rb' mode with 'r'.

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