Writing to a file

suggest change

with open('myfile.txt', 'w') as f:
    f.write("Line 1")
    f.write("Line 2")
    f.write("Line 3")
    f.write("Line 4")

If you open myfile.txt, you will see that its contents are:

Line 1 Line 2 Line 3 Line 4

Python doesn’t automatically add line breaks, you need to do that manually:

with open('myfile.txt', 'w') as f:
    f.write("Line 1\n")
    f.write("Line 2\n")
    f.write("Line 3\n")
    f.write("Line 4\n")

Line 1 Line 2 Line 3 pyLine 4

Do not use os.linesep as a line terminator when writing files opened in text mode (the default); use \n instead.

If you want to specify an encoding, you simply add the encoding parameter to the open function:

with open('my_file.txt', 'w', encoding='utf-8') as f:
    f.write('utf-8 text')

It is also possible to use the print statement to write to a file. The mechanics are different in Python 2 vs Python 3, but the concept is the same in that you can take the output that would have gone to the screen and send it to a file instead.

with open('fred.txt', 'w') as outfile:
    s = "I'm Not Dead Yet!"
    print(s) # writes to stdout
    print(s, file = outfile) # writes to outfile

    #Note: it is possible to specify the file parameter AND write to the screen
    #by making sure file ends up with a None value either directly or via a variable
    myfile = None
    print(s, file = myfile) # writes to stdout
    print(s, file = None)   # writes to stdout

In Python 2 you would have done something like

outfile = open('fred.txt', 'w')
s = "I'm Not Dead Yet!"
print s   # writes to stdout
print >> outfile, s   # writes to outfile

Unlike using the write function, the print function does automatically add line breaks.

Found a mistake? Have a question or improvement idea? Let me know.

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