CMU 15-110: Principles of Computing
Running Code

1. Install Python, IDLE, and pyzo
2. Hello World in Python
3. Python Comments
4. Syntax, Runtime, and Logical Errors
5. Basic Console Output
6. Basic Console Input
7. Importing Modules

1. Install Python, IDLE, and pyzo
   • We will use Python 3.6 or later.
   • We will use Pyzo as our text editor / IDE.
   • There are detailed install instructions here (but use most-current versions of Python and Pyzo).
   • If you are having troubles, or just want some help, go to OH and a TA will gladly assist!


2. Hello World in Python
   • Command typed into shell
     
     print("Hello World!")
   
   
   • Function typed into shell
     
     def helloWorld(): print("Hello World!") helloWorld()
   
   
   • File edited in IDLE
     Download helloWorld.py, edit it in IDLE, and run it.


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


4. Syntax, Runtime, and Logical Errors
   • Syntax Errors (Compile-Time Errors)
     print("Uh oh!) # ERROR! missing close-quote # Python output: # SyntaxError: EOL while scanning string literal
   
   
   • Runtime Errors ("Crash")
     print(1/0) # ERROR! Division by zero! # Python output: # ZeroDivisionError: integer division or modulo by zero
   
   
   • Logical Errors (Compiles and Runs, but is Wrong!)
     print("2+2=5") # ERROR! Untrue!!! # Python output: # 2+2=5


5. Basic Console Output
   print("Carpe") print("diem")


6. Basic Console Input
   • Input a string
     name = input("Enter your name: ") print("Your name is:", name)
   
   
   • A string is not a number!
     n = input("Enter a number: ") print("10 times that number is: ", 10*n)
   
   
7. Importing Modules
   import math print(math.factorial(20))