Installation of Python

• Download the current production version of Python (3.7.3) from the Python Download site.
• Double click on the icon of the file that you just downloaded.
• There should be two options - Install Now and Customize installation. On the same menu screen there should be two options:
  • Install launcher for all users (recommended)
  • Add Python 3.7 to PATH
• Make sure that you check Install launcher for all users and Add Python 3.7 to PATH. Then select Install Now.

Check Installation

• Open up a command (cmd) window.
• Type python -V on the command line.
• It should come back with the correct version of Python.

Writing Your First Python Program

• Create a folder called CS313E on your C:\ drive. You will be storing all your Python programs in this folder.
• Go to Start and either type Run in the Start Search box at the bottom or click on Run.
• Type in notepad in the field called Open.
• In Notepad type in the following program exactly as written:

# File: Hello.py
def main():
  print ("Hello World!")

main()

• Go to File and click on Save as.
• In the field Save in browse for the C: drive and then select the folder CS313E.
• For the field File name remove everything that is there and type in Hello.py.
• In the field Save as type select All Files
• Click on Save. You have just created your first Python program.

Running Your First Program

• Go to Start and click on Run.
• Type cmd in the Open field and click OK.
• A dark window will appear. Type cd C:\ and hit the key Enter.
• If you type dir you will get a listing of all folders in your C: drive. You should see the folder CS313E that you created.
• Type cd CS313E and hit Enter. It should take you to the CS313E folder.
• Type dir and you should see the file Hello.py.
• To run the program, type python Hello.py and hit Enter.
• You should see the line Hello World!
• Congratulations, you have run your first Python program.

Python comes bundled with Mac OS X. But the version that you have is quite likely an older version. Download the latest binary version of Python that runs on your version of Mac OS X and install it on your system. Follow the instructions; they are simple.

If you have an older version of Python on your Mac do NOT uninstall it. You can have various versions of Python without any problems. Restart your computer. Now if you type python in any Terminal window the older version will be called upon and if you type python3 you will be using the newer verson. To check the version you are using, run this command:

python - V

python3 -V

Writing Your First Python Program

• Click on File and then New Finder Window.
• Click on Documents.
• Click on File and then New Folder.
• Call the folder CS313E. You will be storing all class related programs there.
• Click on Applications and then TextEdit.
• Click on TextEdit on the menu bar and select Preferences.
• Select Plain Text.
• Make sure that the Smart Quote is UNCHECKED.
• Close the empty TextEdit window and create a new one by clicking File → New. Now type in the following program, exactly as given:

# File: Hello.py
def main():
  print ("Hello World!")

main()

• From the File menu in TextEdit click on Save As.
• In the field Save As: type Hello.py.
• Select Documents and the file folder CS313E.
• Click Save.

Running Your First Program

• Select Applications, then Utilities and Terminal.
• In your Terminal window type ls and Return. It should give a listing of all the top level folders. You should see the Documents folder.
• Type cd Documents and hit Return.
• Type ls and hit Return and you should see the folder CS313E.
• Type cd CS313E and hit Return.
• Type ls and hit return and you should see the file Hello.py.
• To run the program, type python3 Hello.py and hit Return.
• You should see the line Hello World!
• Congratulations, you have run your first Python program.

Starting IDLE on Mac

• In a Terminal window, type python3. This will start the Python shell. The prompt for that is >>>
• At the Python shell prompt type import idlelib.idle
• This will start the IDLE IDE

Using IDLE on either Windows or Mac

• Start IDLE
• Go to File menu and click on New File
• Type your program in
• Go to File menu and click on Save. Type in filename.py This will save it as a plain text file, which can be opened in in any editor you choose (like Notepad or TextEdit).
• To run your program go to Run and click Run Module