Quiz 5 Material

Question 1

classes create ______ that encapsulate both data and methods

Answer 1

objects

Question 2

variables + methods = ________

Answer 2

attributes

Question 3

what is the return type of math.floor()?

Answer 3

a math object

Question 4

what is math.ceil() called?

Answer 4

a constructor

Question 5

can you import classes?

Answer 5

yes

Question 6

how would you write the heading for a class called MyClass? AKA class definition

Answer 6

class MyClass:

Question 7

what is an instance/object of a class?

Answer 7

it is one particular creation of the class (kind of like a recipe)

Question 8

what is the first method that is in the class and how is it written?

Answer 8

• it is the constructor that is call when you create an object of the class
  def __init__(self, parameters)

Question 9

public vs private attributes

Answer 9

public attributes - which are open to access by anyone
private attributes - which are only available to the class object

Question 10

accessor methods

Answer 10

providing some public means of accessing private elements of our class

Question 11

write a private and public attribute for charge?

Answer 11

private: self.__charge
public: self.charge

Question 12

the __str__ method

Answer 12

it is common practice to include a method that provides a representation of an object as a string

Question 13

are the __init__ method and the __str__ method called by invoking their actual names?

Answer 13

no

Question 14

if we don’t use self, then the variable only exists in the scope of the particular ________

Answer 14

function

Question 15

does self have to be the first parameter?

Answer 15

yes

Question 16

steps for writing to a file

Answer 16

1. open a file for writing – outfile = open(filename, ‘w’) OR with open(filename,’w’) as outfile:
2. write to the file – outfile.write() OR print(…, file=outfile)
3. close the file – outfile.close()

Question 17

what is the difference between opening a file in ‘w’ mode and opening a file in ‘a’ mode

Answer 17

‘w’ mode - OS will erase everything that was already there
‘a’ mode - OS will append to existing file