Chapter 1

• Again, I assume these concepts are familiar. I’m just going to highlight the aspects that are specific to Python.
• Open “In-Class 1”
  • Log into PrairieLearn,
  • navigate to the assessment named “In-Class 1”
  • Set up a group, if you like.
  • Launch the workspace
  • Open playspace
  • “play” with it. Both the markdown and the code.
• Demonstrate some markdown features
  • list
  • code
  • bold/italics
• Demonstrate some python features
  • variables carry from window to window.
  • if you run cell-by-cell, the code goes in execution order, not “top-down”

Variables

• Letters, numbers, underscores.
• Can’t start with a number.
• Convention is to use snake_case not camelCase
• Avoid names that begin with two underscores.
• Doesn’t need to be declared (like with C or Java). Just assign a value (x = 7)
• Can’t be read before being assigned.
  • modify sample code to reference variable that doesn’t exist and show resulting error.
• String literals go in quotes.

Output

• print method
• comma-separated list of items to print.
• Python inserts space between parameters!
  • This is different from many other languages.
  • Give demo.
• print ends with a newline by default.
  • To override: print('No newline', end=' ')
• You can also use string interpolation.
  • Put f before string.
  • Put code to be interpolated in braces.
  • Notice that braces can contain code, not just variable. print(f"The cost with tax is ${cost*1.06}")
  • zyBook uses comma-separated list. You can use whichever technique you prefer.
  • https://www.programiz.com/python-programming/string-interpolation
• Use string interpolation to format floating-point values
• print(f'{myFloat:.2f}')
• You can also use the same pattern to format integers printf(f'{someInt:.05}) to produce leading zeros.

Input

• input() returns the entire line (except the newline) typed by the user as a string
• return value of input is always a string
• use int() function to convert it to an integer.
  • show what happens if you forget conversion
  • f = input() print(f"You entered->{f+4}<-")
• Use float() to convert to floating-point.