W18

Question 1

The most two important computational resources are:

Answer 1

1- Time
2- Space (memory)
Also, we can measure:
- number of operations performed
- order of growth (big O notation)

Question 2

Terminology for describing performance:

What is best case, worst case and average case?

Answer 2

best case: is the minimum running time overall possible inputs of a given size

worst case: is the maximum running time over all possible inputs of a given size

average case: is the average running time over all possible inputs

Question 3

Order of growth ( big O notation) describes what?

Answer 3

the running time in relation to input size (usually the worst case scenario)

Question 4

ways of sorting:

Answer 4

1- bubble sort
2- selection sort
3- merge sort

Question 5

ways of searching:

Answer 5

1- linear search

2- bisection search

Question 6

linear search

Answer 6

1- list does not have to be sorted

2- brute force search???

Question 7

bisection search

Answer 7

1- list must be sorted

2- divide and conquer approach

Question 8

A template that describes a set of objects with the same behaviours ??

Answer 8

A class

Question 9

What is Encapsulation?

Answer 9

1- hiding the implementation details

2- enables changes in the implementation without affecting users of a class

Question 10

An instance(نموذج) of a class?

Answer 10

An object

Question 11

object reference?

Answer 11

The memory location of the object

Question 12

How to check if two objects are aliases (point to the same memory location)?

Answer 12

using (is)
if obj1 is obj2:
print(“Aliases”)

Question 13

How to check if two objects contain same data?

Answer 13

using ( ==)
if obj1 == obj2:
print(“objects contain same data”)

Question 14

How to check if an object is not empty before using it?

Answer 14

using (is)
if obj is None:
…..

Question 15

function vs methos

Answer 15

A method is defined as part of class definition
so, it always has, at least, one parameter which is (self)

Question 16

What is (self reference)?

Answer 16

(self) stores the object reference on which the method was invoked

Question 17

Accessor and Mutator methods:

Answer 17

get

set

Question 18

1- how to use the instance variable inside its class?

2- how to call a method inside a method in the same class?

Answer 18

using (self)
1- self.instanceVariable
2- def x(self,num):
self.addOne(num)

Question 19

should instance variable be encapsulated?

Answer 19

Yes

using accessor and mutator methods

Question 20

static(class) vs instance variables

Answer 20

• both are declared inside a class.
• however, instance variables are declared inside the constructor
• other classes can call the static variable using the class name: class.variable

Question 21

What does a constructor do?

Answer 21

initialize instance variables of an object (creates an object and its instance variables)

Question 22

how to define a constructor?

Answer 22

def __init__(self):

Question 23

All variables are created at the run time?

True or False

Answer 23

True

Question 24

what is a default argument?

Answer 24

def __init__(self, age, name, color = white):

self. age= age
self. name= name
self. color= color

• if the user did not enter a color, then by default the color is white.
• this can be used in any method

Question 25

the special method (__repr__)

Answer 25

Like toString in Jave. ``` def __repr__(self): return self.age+" " + self.color ```

Question 26

I need more reading on the SPECIAL METHODS

Answer 26

to use the standard operators with an object, define the corresponding special methods