Main Function

Resources

• Slides

Let’s review a couple other concepts related to functions in Python.

Main Function

We can also create a main function in Python. The use of a main function in Python is not required at all - Python is designed as a scripting language, meaning we can write code directly in a Python file without using any functions at all. However, it is generally considered good practice to make sure all code is part of a function, and then we can include a main function as the starting point for any program.

So, we can update the example we saw previously to include a main function by simply placing the three function calls in a new function called main, and then including a call to the main function at the bottom of the program:

def foo():
    print("eye")


def bar():
    print("to")


def main():
    foo()
    bar()
    foo()


main()

From here on out in this course, we’ll follow this convention in our complete Python programs. Specifically:

1. All programs must contain a function named main as the starting point of the program.
2. All code in a program must be contained within a function, with the exception of a single call to the main function at the bottom of the program.

This will make our Python programs easy to follow, and it will help us later on down the road if we choose to learn another language such as Java or C# that requires a main function.