5. Loops Practice Quiz and Assignment Work Period

Quick Overview of Day

Use for loops and functions to draw one shape elegantly. Continue working on a Python turtle graphics assignment, focused on repetition and conditionals.

  • CS20-CP1 Apply various problem-solving strategies to solve programming problems throughout Computer Science 20.
  • CS20-FP1 Utilize different data types, including integer, floating point, Boolean and string, to solve programming problems.
  • CS20-FP2 Investigate how control structures affect program flow.
  • CS20-FP3 Construct and utilize functions to create reusable pieces of code.
  • CS20-FP4 Investigate one-dimensional arrays and their applications.

5.1. Practice Problem

../../_images/confusion-17.png

Draw the shape above. You can choose to either:

  • create a function, and repeatedly call that function
  • use repetition without a function (if you choose this method, you will want to use a nested for loop)

5.2. What Does This Program Do?

Note

Your teacher may choose to use the following examples as a class activity, by displaying the examples, and having you take a guess as to what you think each will do before running the code.

What will the following programs output? Why?

5.3. Loops Practice Quiz

5.3.1. Question 1

    loops-practice-quiz1: What shape will the turtle alex draw when the code below is executed?:

    import turtle

the_window = turtle.Screen()
the_window.bgcolor("lightgreen")
alex = turtle.Turtle()
alex.pensize(3)

for i in [0,1,2,3]:
    alex.forward(50)
alex.left(90)
  • No shape will be drawn.
  • Try again!
  • A line segment.
  • Great!
  • A triangle.
  • Try again!
  • A square.
  • Try again! Notice that that alex.left(90) command is not inside the for loop.

5.3.2. Question 2

    loops-practice-quiz2: What shape will the turtle alex draw when the code below is executed?:

    import turtle

the_window = turtle.Screen()
the_window.bgcolor("lightgreen")
alex = turtle.Turtle()
alex.pensize(3)

for i in [0,1,2,3]:
    alex.forward(50)
    alex.left(90)
  • No shape will be drawn.
  • Try again!
  • A line segment.
  • Try again! This time, the alex.left(90) is included in the for loop.
  • A triangle.
  • Try again!
  • A square.
  • Great!

5.3.3. Question 3

In the following code, how many lines does this code print?:

for number in [10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]:
    print("I have", number, "cookies.  I'm going to eat one.")

5.3.4. Question 4

    loops-practice-quiz3: The following will print a line showing the number 4:

    for i in range(4):
    print(i)
  • True
  • Nope. Remember that range(4) will create a list with elements [0,1,2,3].
  • False
  • Great!

5.3.5. Question 5

What is the last line that this code will print?:

i = 1
while (i <= 3):
    i = i + 1
    print(i)

5.4. Turtle Graphics Assignment

Use the rest of this class time to keep working on your current Python assignment (possibly a turtle graphics drawing, with a focus on looping and conditionals).

Next Section - 1. Fruitful Functions and Variable Scope