Getting Started

1. Logistics and Preliminaries
2. Running Python
3. Hello World in Python
4. Python Comments
5. Basic Console Output
6. Importing Modules
7. More Logistics and Preliminaries
8. Syntax, Runtime, and Logical Errors
9. Basic Console Input

1. Logistics and Preliminaries   video
   • Course web site (http://www.cs.cmu.edu/~112)
   • Course Policies / Syllabus
   • Course Schedule
   • Waitlist policy
   • 15-112 vs 15-110


2. (Optional) Running Python   video
   Note: Setting up VSCode is not a course requirement until the Term Project.
   • Install Python 3.11.x from python.org's download page.
   • Install VSCode (see the Getting Started with VSCode notes here)
   • Run VSCode (the default Python text editor / IDE)
   • Edit your Python file
   • Run your code (command-B or control-B in VSCode once you followed our setup instructions)


3. Hello World in Python   video
   • Command typed into shell
     

     print("Hello World!")

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   • File edited in VSCode
     Download helloWorld.py, edit it in VSCode, and run it.


4. Python Comments   video

   print("Hello World!") # This is a comment
   # print "What will this line do?"

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5. Basic Console Output   video
   • Basic print function

     print("Carpe")
     print("diem")

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   • Print on same line

     # You can separate multiple values with commas
     print("Carpe", "diem")
     
     # You can also use end="" to stay on the same line
     print("Carpe ", end="")
     print("diem")

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   • Print using f strings

     x = 42
     y = 99
     # Place variable names in {squiggly braces} to print their values, like so:
     print(f'Did you know that {x} + {y} is {x+y}?')

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6. Importing Modules   video
   • Call without importing

     print(math.factorial(20))  # we did not first import the math module
     
     # Python output:
     #   NameError: name 'math' is not defined

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   • Call with importing

     import math
     print(math.factorial(20))  # much better...

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7. More Logistics and Preliminaries
   • Programming vs Computer Science
   • Course Objectives / TP Gallery (see sidebar)


8. Syntax, Runtime, and Logical Errors   video
   • Syntax Errors (Compile-Time Errors)

     print("Uh oh!) # ERROR!  missing close-quote
     
     # Python output:
     #   SyntaxError: EOL while scanning string literal

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   • Runtime Errors ("Crash")

     print(1/0) # ERROR!  Division by zero!
     
     # Python output:
     #   ZeroDivisionError: integer division or modulo by zero

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   • Logical Errors (Compiles and Runs, but is Wrong!)

     print("2+2=5") # ERROR!  Untrue!!!
     
     # Python output:
     #   2+2=5

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9. Basic Console Input   video
   • Input a string

     name = input("Enter your name: ")
     print("Your name is:", name)

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   • Input a number (error!)

     x = input("Enter a number: ")
     print("One half of", x, "=", x/2) # Error!

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   • Input a number with int()

     x = int(input("Enter a number: "))
     print("One half of", x, "=", x/2)

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