I've very recently migrated to Python 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

But in 3.5, on the if 'some-pattern' in tmp: continue line, I get an error which says:

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

I was unable to fix the problem using .decode() on either side of the in, nor could I fix it using

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

What is wrong, and how do I fix it?

解决方案

You opened the file in binary mode:

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

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

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

if b'some-pattern' in tmp: continue

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