if __name__ == “__main__”

You will see a very common conditional statement used in many Python examples. This is what it looks like:

if __name__ == "__main__":
    # do something!

You will see this at the end of a file. This tells Python that you only want to run the following code if this program is executed as a standalone file. I use this construct a lot to test that my code works in the way I expect it to. We will be discussing this later in the course, but whenever you create a Python script, you create a Python module. If you write it well, you might want to import it into another module. When you do import a module, it will not run the code that’s under the conditional because __name__ will no longer equal "__main__". We will look at this again in Chapter 11 when we talk about classes.

Wrapping Up

We’ve covered a fair bit of ground in this chapter. You have learned how to use conditional statements in several different ways. We have also spent some time getting acquainted with Boolean operators.