TypeError a bytes-like object is required not str when writing to a file in Python3

Question

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

User · Answer

I got this error when I was trying to convert a char (or string) to bytes, the code was something like this with Python 2.7:

# -*- coding: utf-8 -*-
print( bytes('ò') )

This is the way of Python 2.7 when dealing with unicode chars.

This won't work with Python 3.6, since bytes require an extra argument for encoding, but this can be little tricky, since different encoding may output different result:

print( bytes('ò', 'iso_8859_1') ) # prints: b'\xf2'
print( bytes('ò', 'utf-8') ) # prints: b'\xc3\xb2'

In my case I had to use iso_8859_1 when encoding bytes in order to solve the issue.

Hope this helps someone.

User · Answer

why not try opening your file as text   with open fname   rt   as f      lines    x strip   for x in f readlines      Additionally here is a link for python 3 x on the official page   https   docs python org 3 library io html And this is the open function  https   docs python org 3 library functions html open  If you are really trying to handle it as a binary then consider encoding your string

User · Answer

You can encode your string by using  encode    Example    Hello World  encode

User · Answer

Use encode   function along with hardcoded String value given in a single quote   Ex   file write answers i      n  encode      OR  line split             encode

User · Answer

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    gt  gt  gt  s bytes  hello    gt  gt  gt  type s   lt type  str  gt

User · Answer

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

User · Answer

You opened the file in binary mode   The following code will throw   a TypeError  a bytes-like object is required  not  str    for line in lines      print type line     lt class  bytes  gt      if  substring  in line         print  success     The following code will work - you have to use the decode   function   for line in lines      line   line decode       print type line     lt class  str  gt      if  substring  in line         print  success

User · Answer

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   lt  1             break     print  data    mysock close    adding the  quot b quot  before  GET http   www py4inf com code romeo txt HTTP 1 0 n n  solved my problem

User · Answer

You have to change from wb to w    def   init   self       self myCsv   csv writer open  Item csv    wb         self myCsv writerow   title    link      to   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

[python] TypeError: a bytes-like object is required, not 'str' when writing to a file in Python3

Examples related to python

Examples related to python-3.x

Examples related to string

Examples related to file

Examples related to byte