Inheritance

What type of inheritance is illustrated in the following Python code?

• Multi-level inheritance

• Multiple inheritance

• Hierarchical inheritance

• Single-level inheritance

Answer explanation

In multiple inheritance, two or more subclasses are derived from the superclass as shown in the above piece of code.

What will be the output of the following Python code?

• A A

• A B

• B B

• An exception is thrown

Answer explanation

obj1.two() invokes the method two() in class A which returns ‘A’ and obj2.two() invokes the method two() in class B which returns ‘B’.

Which of the following is not a type of inheritance?

• Double-level

• Multi-level

• Single-level

• Multiple

What will be the output of the following Python code?

• Error, the syntax of the invoking method is wrong

• The program runs fine but nothing is printed

• 1 0

• 1 2

Answer explanation

The invoking method has been properly implemented and hence x=1 and y=2.

What will be the output of the following Python code?

• Error because class B inherits A but variable x isn’t inherited

• 0 0

• 0 1

• Error, the syntax of the invoking method is wrong

Answer explanation

The invoking method has been properly invoked, variable x from the main class has been properly inherited and it can also be accessed.

Suppose B is a subclass of A, to invoke the init method in A from B, what is the line of code you should write?

• A.__init__(self)

• B.__init__(self)

• A.__init__(B)

• B.__init__(A)

Answer explanation

To invoke the init method in A from B, either of the following should be written: A.__init__(self) or super( ).__init__( ).

What will be the output of the following Python code?

• Invalid syntax for inheritance

• Error because when object is created, argument must be passed

• Nothing is printed

• A disp( )

Answer explanation

Class B inherits class A hence the function disp () becomes part of class B’s definition. Hence disp() method is properly executed and the line is printed.