Drill 14 Solution

Question 1

Several of the questions below will refer to this dataclass:

@dataclass
class Course:
  code : str
  students : list # of strings

Consider the code below. Write a line of code code to add 'Leo' to the end of the list of students in the first course in c.

Answer

c[0].students.append('Leo')

Question 2

Consider the code below (same as above). How many memory locations would be needed store the information in 'c'?

c = [Course('csci0111', ['Eli', 'Rohan']), Course('csci0170', [])]

Answer

5

We want to consider all the lists and Courses that are created: 1 for the list of courses, 1 for each of the courses, and 1 for each of the courses' lists.

Question 3

Consider the code below:

course1 = Course('csci0111', ['Monica', 'Julia'])
course2 = Course('csci0112', ['Giselle', 'Colton'])
course3 = course1

Fill in the blanks in the program directory and memory:

Program directory:

name	value
course1	loc 1002
course2	BLANK1
course3	BLANK2

Memory:

name	data
loc 1001	BLANK3
loc 1002	Course('csci0111', loc 1001)
loc 1003	['Giselle', 'Colton']
loc 1004	Course('csci0112', BLANK4)

Answer

BLANK1: loc 1004

BLANK2: loc 1002

BLANK3: ['Monica', 'Julia']

BLANK4: loc 1003

Question 4

Is there any program that will produce this program directory and memory?

Program directory:

name	value
course1	loc 1002
course2	loc 1002

Memory:

name	data
loc 1001	['Monica', 'Julia']
loc 1002	Course('csci0111', loc 1003)
loc 1003	['Giselle', 'Colton']
loc 1004	course1

( ) Yes
( ) No, two values cannot point at the same location in memory
( ) No, data in memory cannot refer to names
( ) No, loc 1002 cannot refer to loc 1003

Answer

No, data in memory cannot refer to names

Two values can point at the same location in memory–for instance, if we run course1 = course2. Data can refer to later memory locations–for instance, if we run course1.students = ['Giselle', 'Colton'].

Question 5

Imagine running the following program:

course1 = Course('csci0111', ['Julia', 'Colton'])
course2 = Course(course1.code, course1.students)

Which of these would be the resulting program directory and memory?

OPTION 1

Program directory:

name	value
course1	loc 1002
course2	loc 1002

Memory:

name	data
loc 1001	['Julia', 'Colton']
loc 1002	Course('csci0111', loc 1001)

OPTION 2

Program directory:

name	value
course1	loc 1002
course2	loc 1003

Memory:

name	data
loc 1001	['Julia', 'Colton']
loc 1002	Course('csci0111', loc 1001)
loc 1003	Course('csci0111', loc 1001)

OPTION 3

Program directory:

name	value
course1	loc 1002
course2	loc 1003

Memory:

name	data
loc 1001	['Julia', 'Colton']
loc 1002	Course('csci0111', loc 1001)
loc 1003	loc 1002

OPTION 4

Program directory:

name	value
course1	loc 1002
course2	loc 1004

Memory:

name	data
loc 1001	['Julia', 'Colton']
loc 1002	Course('csci0111', loc 1001)
loc 1003	['Julia', 'Colton']
loc 1004	Course('csci0111', loc 1001)

( ) OPTION 1
( ) OPTION 2
( ) OPTION 3
( ) OPTION 4

Answer

OPTION 2