Unexpected output write

[minmanrox]

I've just taken up coding and have been teaching myself out of Simon Monk's "Programming the Raspberry Pi" book. On p79, he demonstrates how to write a file in the python shell. When I copy his code into my shell, instead of writing a file, it gives me the length of the string I tried to write.
I've tried different files, different variable names, restarting python, and trying different strings, but it's always the same result. I'm running python 3 on Raspbian.
My shell looks like this:

>>> f = open('test.txt', 'w')
>>> f.write('words')
5
>>>

hoping you can help
[email protected]

[Windspar]

That the right result. If you total every write. Then you know how many chars are in the file.
You have to close file. closing a file will flush data. Saving it to file.
If you don't close file. It a memory leak.

[Larz60+]

better to use:

with open('test.txt', 'w') as f:
    f.write(...)

that way you don't have to remember to close as it's done automatically

[minmanrox]

Awesome makes sense. Thank you