[Zero To Python] Day 8 - Saving To Text Files
The files are in the computer?!
Now that we’ve played with strings quite a bit, it’s time to save journal entries to a text file. This will allow a journal entry to persist across multiple user sessions. In short, this makes our daily journal program useful!
So let’s get started.
Writing To A File In Python
The first thing we are going to do is create a new python file called file.py. This is where we will write a bit of code to get a handle on opening up a file and writing some text. Inside file.py write the following code:
Before we run the code, let me walk through it real quick. We start with creating a variable fake_text and assign it a text string. The code prints out the string to give us an idea of what the value of fake_text is.
Next we get to the new bit. The code creates a variable called my_file and sets its value to whatever the open() function returns (which is a file object). We pass in the name of the file we are opening test.txt and the mode flag w. The next line writes the value of the fake_text variable to the file. The last line calls close() on our file which closes the file.
When you run file.py you get the following output:
And if you look inside test.txt it will have abc123 and a newline saved there.
That is the basics of writing to a file in Python.
Writing Journal Entries To File
Now let’s go back to input.py and add some new code to the end of the file. After your final print statement, add the following code:
What this code does is takes the user input of journal_date and journal_text and writes it to a file instead of just printing it out to the screen. The code is very similar to the print calls we already had, but uses my_file.write() instead of print(). Also, newline characters are added to make the output in the file match our screen output.
If you run input.py you get the following output:
And the journal entry should be written to the test.txt file.
Pretty cool, right?
Assignment
The assignment today is to update the input.py file to include code to write journal entries to a file. This isn’t overly complex code, but it is something that is worth understanding going forward.
For bonus, you could mess around with text formatting and other things when writing to file.
Useful Links
Moving From Prototype To Reality
As you can probably tell, we are quickly moving from a simple prototype into a useful program. In the next few days we will be adding even more useful features to this project. Before you know it, you’ll have a fully working version of the designs we started with.
So, keep having fun with this and I’ll see you in the next lesson!
-Brian