Test&Track

The car here is inside the class, so is an object

The car is an object, as it represents a specific car

The car in this image is the class itself. The 'car' class has attributes and methods.

The car in this case is just a procedure as it has only two 'objects'

an example of the attributes and templates of the red class

an example of an instance of a class (i.e an object)

an example of an attribute

an example of a class

method

function

object class

attribute

Note: Not all languages call this the constructor, but it is useful to know the term.

object

attribute list

class template

object orientated approach

class test:
     def __init__(self,a="Hello World"):
         self.a=a
 
     def display(self):
         print(self.a)
obj=test()
obj.display()

Hello World” is displayed.

A logic error occurs as 'display' is not a valid attribute

Error - there is nothing in the display method

A run time error occurs

then it would be created

then it would be incorporated and embedded into the object first

None of the above

then it would be deleted

To access the attribute of the object

to check if an attribute exists or not

None of the above

to delete the attribute of an object

 class test:
     def __init__(self,a):
         self.a=a
 
     def display(self):
         print(self.a)
obj=test()
obj.display()

Error as one argument is required to create the object

Displays 0, which is the automatic default value

The letter 'x' is printed.

Runs normally, doesn’t display anything

>>> class A:
	def __init__(self,b):
		self.b=b
	def display(self):
		print(self.b)
>>> obj=A("Hello")
>>> del obj

The class is 'A', the object is 'obj', and obj is being deleted

There is no class or object defined here

None of the above

The class is 'A', the object is 'b' and the class is being deleted on the last line

abstraction

instant-creation

encapsulation

Instantiation

a)

class A:
    return
b)

class A:
    pass
c)

class A:

class Student:
      def __init__(self,name,test_score): #this init method is the first method to be invoked when you create an object
          #ensure you initialise all your attributes in the init method
          self.name=name
          self.test_score=test_score
          
        #=======creating a method to see if the student has met their target
      def hasAchievedTarget(self):
         #the self is a default parameter that the methods of your class accept, in order to use the attributes of your class
        if self.test_score>=90:
            print("Target met, Well done!")
        else:
            print("Target not achieved")

student1=Student("Ruth Marvin",21)

All of the above are valid

student1=Student("Ruth Marvin",21,self,0)

Student("Ruth Marvin",21)

class Student:
      def __init__(self,name,test_score): #this init method is the first method to be invoked when you create an object
          #ensure you initialise all your attributes in the init method
          self.name=name
          self.test_score=test_score
          
        #=======creating a method to see if the student has met their target
      def hasAchievedTarget(self):
         #the self is a default parameter that the methods of your class accept, in order to use the attributes of your class
        if self.test_score>=90:
            print("Target met, Well done!")
        else:
            print("Target not achieved")
student1=Student("Jonathan",21) #the process of creating an object is called instantiation.
print(student1.name)
print(student1.test_score)
student1.hasAchievedTarget()

Jonathan, 21, Target met, Well done!

Jonathan, 21, Target not achieved

Error message - as there is no method to print the target

from turtle import*
class Planet:
    #self is how we refer to things in the clas from within itself. .self is the first parameter in any function defined inside a class
    #to access functions and variables inside the class, their name must be preceded with self and a full-stop (e.g. self.variable_name)
    def __init__(self,x,y,radius):
        self.radius=radius #circles need a radius in order to be defined
        self.x=x
        self.y=y
            
    canvas = Screen()
    canvas.setup(800,800)
    turtle = Turtle()
    
    def circumference(self):
        return 2*3.1415*self.radius

    def scaleSize(self,scale):
        self.radius=self.radius*scale

    def draw(self,colour):
        self.turtle.goto(self.x,self.y) #go to (x,y+radius)
        self.turtle.color(colour)
        self.turtle.dot(self.radius) #dot takes the circle diameter as a parameter (size)
        
#Specify width and height below e.g. 100,200
planet1=Planet(-200,-100,200)
planet1.draw("red")
planet2=Planet(300,300,100)
planet2.draw("black")

None of the above

There are three classes (planet, planet1 and planet2)

Planet' is the class, and there are two objects (planet1 and planet2)

There are two classes (planet1 and planet2) and one template object 'Planet'

Module mybox
   Class Box
      Public length As Double   ' Length of a box
      Public breadth As Double  ' Breadth of a box
      Public height As Double   ' Height of a box
   End Class
   Sub Main()
      Dim Box1 As Box = New Box()        ' Declare Box1 of type Box
      Dim Box2 As Box = New Box()        ' Declare Box2 of type Box
      Dim volume As Double = 0.0         ' Store the volume of a box here
      
      ' box 1 specification
      Box1.height = 5.0
      Box1.length = 6.0
      Box1.breadth = 7.0
      
      ' box 2 specification
      Box2.height = 10.0
      Box2.length = 12.0	
      Box2.breadth = 13.0
      
      'volume of box 1
      volume = Box1.height * Box1.length * Box1.breadth
      Console.WriteLine("Volume of Box1 : {0}", volume)
      
      'volume of box 2
      volume = Box2.height * Box2.length * Box2.breadth
      Console.WriteLine("Volume of Box2 : {0}", volume)
      Console.ReadKey()
   End Sub
End Module

Volume of Box1 : 210 and Volume of Box2 : 1560

None of the above

Error

Volume of Box 1: 10

Preview

02 - Classes and Objects