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.readli         


        

Answer 1

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))# 
    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))# 
    if 'substring' in line:
       print('success')