CPSC120A
Fundamentals of Computer Science I

Being able to read code and figure out what it will do when executed is called tracing the code. Tracing code is an important skill to have for debugging runtime errors. Tracing code helps figure out where the actual execution of a program deviates from the expected execution and thereby determine where and how to fix it.

1. Draw what the following Python program will draw when run.

   import turtle
   
   line_length = 100
   turn_angle = 90
   turtle.forward(line_length)
   turtle.left(turn_angle)
   
   line_length = 75
   turtle.forward(line_length)
   turtle.left(turn_angle)
   
   line_length = 50
   turtle.forward(line_length)
   turtle.left(turn_angle)
   
   line_length = 25
   turtle.forward(line_length)
   turtle.left(turn_angle)
   
   turtle.mainloop()

2. Draw what the following Python program will draw when run.

   import turtle
   
   line_length = 100
   turn_angle = 90
   turtle.left(turn_angle)
   turtle.forward(line_length)
   
   line_length = 75
   turtle.left(turn_angle)
   turtle.forward(line_length)
   
   line_length = 50
   turtle.left(turn_angle)
   turtle.forward(line_length)
   
   line_length = 25
   turtle.left(turn_angle)
   turtle.forward(line_length)
   
   turtle.mainloop()

3. Draw what the following Python program will draw when run.

   import turtle
   
   x = 100
   y = 100
   turtle.goto(x, y)
   turtle.up()
   
   x = -100
   y = 100
   turtle.goto(x, y)
   turtle.down()
   
   x = 100
   y = -100
   turtle.goto(x, y)
   turtle.up()
   
   x = -100
   y = -100
   turtle.goto(x, y)
   turtle.down()
   
   turtle.mainloop()

4. Draw what the following Python program will draw when run.

   import turtle
   
   x = 100
   y = 100
   turtle.up()
   turtle.goto(x, y)
   
   x = -100
   y = 100
   turtle.down()
   turtle.goto(x, y)
   
   x = 100
   y = -100
   turtle.up()
   turtle.goto(x, y)
   
   x = -100
   y = -100
   turtle.down()
   turtle.goto(x, y)
   
   turtle.mainloop()