Question

What is the output of the following? 1. a = 5 b = a a = 7 print(b) 2. a = [5] b = a a[0] = 7 print(b) Explain the output.

Answer 1

I. a = 5         # a is initially 5

  b = a         # b becomes a which is 5

  a = 7         # Now, a becomes 7

  print(b)   # b is printed which is 5

  Hence, after execution a = 7 and b = 5.

II. a = [5]      # a is initially a list with a single value 5

   b = a         # b now refers to the same list containing 5 in a

   a[0] = 7    # Now, if a changes the value of the list then, it is reflected in b too as they both refer to the same list

   print(b)   # b is printed which is [7]

   Hence, after execution a = b = [7].