Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

Getting started with "Hello World"

From: Python 3 Essential Training

Video: Getting started with "Hello World"

As we start the Python Quick Start, we're going to use the traditional "Hello, World!" program. And purpose of "Hello, World!" is not an exercise to find the simplest form of code in a particular language, or anything like that. It's actually to learn about the development environment, to learn about what we call the development cycle: what it takes to edit, and to test, and to change, and to test and to run code in a particular environment. And so for this purpose we use the simplest form of a program itself, so that that can get out of the way and then we can focus on the environment.

Getting started with "Hello World"

As we start the Python Quick Start, we're going to use the traditional "Hello, World!" program. And purpose of "Hello, World!" is not an exercise to find the simplest form of code in a particular language, or anything like that. It's actually to learn about the development environment, to learn about what we call the development cycle: what it takes to edit, and to test, and to change, and to test and to run code in a particular environment. And so for this purpose we use the simplest form of a program itself, so that that can get out of the way and then we can focus on the environment.

In this case, I've this up here on the screen in Eclipse. And this is Eclipse using Pydev, which is a Python development environment that runs inside of Eclipse. Eclipse is an integrated development environment originally written for developing in Java, but it has plug- ins for a lot of different languages. And Pydev is actually a pretty good plug-in for the Python language. And so, we'll be using this throughout this course. You do not have to use Eclipse, and if you have some other development environment that you prefer, or you just want to use an editor and a command line, that's perfectly fine.

You can do all of the exercises; you do not need to use Eclipse. The reason that I'm using Eclipse is because it's convenient for the purpose of teaching. I've got everything that I need right up here on the screen. I can run code, I get the results of code, and it works well for the purpose of teaching, but you don't need to use it for your development work. And you do not need to use it to follow along in the exercises. In Eclipse, if I want to run this Hello, World!, I simply click on this Run button up here, and it'll ask me, How I want to run it? and I'm going to select Python Run.

I only need to do this the first time I run a script. So I'm going to say OK. And here we have the result down here: "Hello, World!" If I were running this in another environment and I actually have this script loaded up here on a Unix Server - this is my Unix Server - there is the script, you see it's exactly the same. And if run it I say ./hello.py, and it runs it. An important part of this is this shebang line.

If we look here in Eclipse, we see this shebang line here. In many environments, mostly Unix- based environments, but this includes Macintosh and it includes many, many web servers that are running Unix-based operating systems, like Linux or PSD, this shebang line is actually very important. It's called a shebang line because it's starts with a hash and then has an exclamation mark, which is sometimes called a bang. And then after that it has the path to the interpreter that will be used to run the script.

When the script is executed and the shell sees it, it will look here for the interpreter and then use that to run the script. So sometimes you'll see a bash up here, or Perl, or something like that. And all that's doing is it's telling the shell to use that interpreter to run whatever script is there. For Python, it's going to be something like this. It might be #!/usr/bin/python3. It might be #!/usr/local/bin/python3. It might be #!/usr/bin/env python3, something like that.

In this case, I'm using #!/usr/bin/python3 because I know that, that works in the environments that I'm using. And if it doesn't, then I'll make a symbolic link or something and make it work. So if you're running this on a Unix-based operating system, you'll want to do ls -l and look at the file permissions, and make sure that it has executable permissions. If it doesn't, you can make it executable by typing chmod, or as we pronounce it chmod 755, which makes it editable and executable for your user ID, and then the name of the file.

And that will make it executable. And then you can execute it with ./ or however it is that you do that on your system. So that is the development environment that we will be using. For the most part, we're going to using Eclipse. And so we'll be running scripts like this. Save it and Run it. It'll run here in the Console. So you're going to want to take the opportunity, using this "Hello, World!" script, to learn about the development cycle and whatever environment you're using, especially if it's not Eclipse, to follow along with the exercises in this course.

Show transcript

This video is part of

Image for Python 3 Essential Training
Python 3 Essential Training

87 video lessons · 39355 viewers

Bill Weinman
Author

 
Expand all | Collapse all
  1. 5m 14s
    1. Welcome
      1m 32s
    2. Understanding prerequisites for Python
      2m 4s
    3. Using the exercise files
      1m 38s
  2. 33m 29s
    1. Getting started with "Hello World"
      4m 43s
    2. Selecting code with conditionals
      4m 45s
    3. Repeating code with a loop
      4m 13s
    4. Reusing code with a function
      2m 43s
    5. Creating sequences with generator functions
      2m 46s
    6. Reusing code and data with a class
      4m 39s
    7. Greater reusability with inheritance and polymorphism
      7m 17s
    8. Handling errors with exceptions
      2m 23s
  3. 22m 32s
    1. Installing Python 3 and Eclipse for Windows
      11m 24s
    2. Installing Python 3 and Eclipse for Mac
      11m 8s
  4. 28m 0s
    1. Creating a main script
      3m 27s
    2. Understanding whitespace in Python
      4m 8s
    3. Commenting code
      3m 28s
    4. Assigning values
      3m 37s
    5. Selecting code and values with conditionals
      4m 46s
    6. Creating and using functions
      3m 54s
    7. Creating and using objects
      4m 40s
  5. 31m 23s
    1. Understanding variables and objects in Python
      2m 46s
    2. Distinguishing mutable and immutable objects
      2m 41s
    3. Using numbers
      3m 34s
    4. Using strings
      6m 38s
    5. Aggregating values with lists and tuples
      4m 55s
    6. Creating associative lists with dictionaries
      4m 24s
    7. Finding the type and identity of a variable
      4m 45s
    8. Specifying logical values with True and False
      1m 40s
  6. 9m 42s
    1. Selecting code with if and else conditional statements
      2m 22s
    2. Setting multiple choices with elif
      2m 14s
    3. Understanding other strategies for multiple choices
      2m 38s
    4. Using the conditional expression
      2m 28s
  7. 11m 26s
    1. Creating loops with while
      1m 27s
    2. Iterating with for
      3m 54s
    3. Enumerating iterators
      3m 22s
    4. Controlling loop flow with break, continue, and else
      2m 43s
  8. 23m 28s
    1. Performing simple arithmetic
      2m 14s
    2. Operating on bitwise values
      3m 30s
    3. Comparing values
      3m 32s
    4. Operating on Boolean values
      2m 59s
    5. Operating on parts of a container with the slice operator
      6m 52s
    6. Understanding operator precedence
      4m 21s
  9. 11m 34s
    1. Using the re module
      1m 4s
    2. Searching with regular expressions
      3m 12s
    3. Replacing with regular expressions
      3m 29s
    4. Reusing regular expressions with re.compile
      3m 49s
  10. 9m 10s
    1. Learning how exceptions work
      1m 18s
    2. Handling exceptions
      4m 15s
    3. Raising exceptions
      3m 37s
  11. 23m 1s
    1. Defining functions
      6m 23s
    2. Using lists of arguments
      2m 26s
    3. Using named function arguments
      4m 32s
    4. Returning values from functions
      1m 55s
    5. Creating a sequence with a generator function
      7m 45s
  12. 47m 29s
    1. Understanding classes and objects
      5m 12s
    2. Using methods
      6m 12s
    3. Using object data
      10m 4s
    4. Understanding inheritance
      5m 11s
    5. Applying polymorphism to classes
      7m 13s
    6. Using generators
      9m 48s
    7. Using decorators
      3m 49s
  13. 18m 54s
    1. Understanding strings as objects
      3m 25s
    2. Working with common string methods
      5m 24s
    3. Formatting strings with str.format
      5m 31s
    4. Splitting and joining strings
      2m 49s
    5. Finding and using standard string methods
      1m 45s
  14. 25m 27s
    1. Creating sequences with tuples and lists
      4m 6s
    2. Operating on sequences with built-in methods
      5m 50s
    3. Organizing data with dictionaries
      4m 56s
    4. Operating on character data with bytes and byte arrays
      10m 35s
  15. 11m 46s
    1. Opening files
      2m 4s
    2. Reading and writing text files
      4m 33s
    3. Reading and writing binary files
      5m 9s
  16. 21m 27s
    1. Creating a database with SQLite 3
      6m 56s
    2. Creating, retrieving, updating, and deleting records
      7m 31s
    3. Creating a database object
      7m 0s
  17. 18m 27s
    1. Using standard library modules
      8m 0s
    2. Finding third-party modules
      5m 47s
    3. Creating a module
      4m 40s
  18. 23m 11s
    1. Dealing with syntax errors
      8m 19s
    2. Dealing with runtime errors
      4m 0s
    3. Dealing with logical errors
      4m 22s
    4. Using unit tests
      6m 30s
  19. 19m 56s
    1. Normalizing a database interface
      6m 39s
    2. Deconstructing a database application
      8m 9s
    3. Displaying random entries from a database
      5m 8s
  20. 29s
    1. Goodbye
      29s

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Python 3 Essential Training.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.