Python Coding Challange - Question With Answer

 

a = [1, 2, 3]
b = a.copy()
a += [4, 5]
print(a, b)

(a) [1, 2, 3, 4, 5] [1, 2, 3]
(b) [1, 2, 3, 4, 5] [1, 2, 3, 4, 5]
(c) [1, 2, 3, 4, 5] [4, 5]
(d) Error

Explanation:

1. a = [1, 2, 3]
   • A list a is created with the elements [1, 2, 3].
     
     
     
2. b = a.copy()
   • The copy() method creates a shallow copy of the list a and assigns it to b.
   • Now, b contains [1, 2, 3], and it is a separate object in memory from a. Modifying a will not affect b.
3. a += [4, 5]
   • The += operator extends the list a by appending the elements [4, 5] to it. This operation modifies a in place and does not create a new list.
   • After this step, a becomes [1, 2, 3, 4, 5].
print(a, b)
• a is now [1, 2, 3, 4, 5].
• b, which is a copy of the original a, remains unchanged as [1, 2, 3].
  
  
  

  Key Concepts:

  1. Shallow Copy:

     • The copy() method creates a new list with the same elements as the original list. However, the two lists are independent; modifying one does not affect the other (unless the elements themselves are mutable objects like nested lists).

  2. In-place Modification:

     • The += operator modifies the original list a in place by appending elements to it, rather than creating a new list.