Intro to Python Fundamentals

Learning objective: By the end of this lesson, students will be able to leave code comments and print data to the console.

Comments

Single-line comments in Python start with the # character and continue to the end of the line.

# This is a comment! Python will ignore it.

Everything on that line after the # is ignored when the code is evaluated, but you can place code to be executed before the # on the same line.

To make multiline comments, use three quotes (either as """ double quotes or ''' single quotes) wrapped around your comments, or use the # character at the start of each line:

"""
this is a
multiline comment
"""

'''
this is also a multiline comment
you can use either set of quotes
'''

# this is a
# multiline comment

Multiline comments are often used to document what a function or module does; therefore, they are sometimes referred to as docstrings.

Printing to the console

In Python, we use the print() function to print a message to the console.

print("Hello, world!") # prints: Hello, world!

Executing Python

Any Python script can be executed from the terminal using this command:

python3 <filename>.py

Replacing <filename> (including the < and the >) with the name of the python file you’d like to execute.

For example, to execute the intro_to_python.py file, use:

python3 intro_to_python.py

You should see the text you passed to the print() function printed to the console.