Python Coding Challange - Question With Answer(01161224)

 

What will the following code output?

a = [1, 2, 3]
b = a[:]
a[1] = 5
print(a, b)

[1, 5, 3] [1, 5, 3]
[1, 2, 3] [1, 2, 3]
[1, 5, 3] [1, 2, 3]
Error

Step-by-Step Explanation:

1. a = [1, 2, 3]
   • A list a is created with elements [1, 2, 3].
2. b = a[:]
   • The slicing operation a[:] creates a shallow copy of the list a and assigns it to b.
   • At this point:
     • a and b are two separate objects in memory.
     • b contains the same elements as a, but any changes made to a will not affect b, and vice versa.
3. a[1] = 5
   • The element at index 1 of list a (which is 2) is replaced with 5.
   • After this modification:
     • a becomes [1, 5, 3].
     • b remains unchanged as [1, 2, 3].
print(a, b)
• The print() function outputs the current values of a and b:
• a is [1, 5, 3].
• b is [1, 2, 3].

Output: [1, 5, 3] [1, 2, 3]

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Key Concept:

• Slicing ([:]) creates a shallow copy of the list.
  Changes made to the original list a do not affect the copied list b, because they are now stored in different memory locations.