TypeError: a bytes-like object is required, not 'str' when writing to a file in Python3
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
After upgrading to 3.5, I'm getting the:
TypeError: a bytes-like object is required, not 'str'
error on the last line (the pattern search code).
I've tried using the
.decode() function on either side of the statement, also tried:
if tmp.find('some-pattern') != -1: continue
- to no avail.
I was able to resolve almost all 2:3 issues quickly, but this little statement is bugging me.
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
if b'some-pattern' in tmp: continue
or open the file as a textfile instead by replacing the
'rb' mode with
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You can encode your string by using
Like it has been already mentioned, you are reading the file in binary mode and then creating a list of bytes. In your following for loop you are comparing string to bytes and that is where the code is failing.
Decoding the bytes while adding to the list should work. The changed code should look as follows:
with open(fname, 'rb') as f: lines = [x.decode('utf8').strip() for x in f.readlines()]
The bytes type was introduced in Python 3 and that is why your code worked in Python 2. In Python 2 there was no data type for bytes:
>>> s=bytes('hello') >>> type(s) <type 'str'>
You have to change from wb to w:
def __init__(self): self.myCsv = csv.writer(open('Item.csv', 'wb')) self.myCsv.writerow(['title', 'link'])
def __init__(self): self.myCsv = csv.writer(open('Item.csv', 'w')) self.myCsv.writerow(['title', 'link'])
After changing this, the error disappears, but you can't write to the file (in my case). So after all, I don't have an answer?
Source: How to remove ^M
Changing to 'rb' brings me the other error: io.UnsupportedOperation: write
for this small example: import socket
mysock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) mysock.connect(('www.py4inf.com', 80)) mysock.send(**b**'GET http://www.py4inf.com/code/romeo.txt HTTP/1.0\n\n') while True: data = mysock.recv(512) if ( len(data) < 1 ) : break print (data); mysock.close()
adding the "b" before 'GET http://www.py4inf.com/code/romeo.txt HTTP/1.0\n\n' solved my problem
Use encode() function along with hardcoded String value given in a single quote.
file.write(answers[i] + '\n'.encode())
line.split(' +++$+++ '.encode())