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GATE DA 2026 | Python & DS | Memory Based | Question 40

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0 0 votes

Consider the following Python code:

def outer():
    x = []
    def inner(val):
        x.append(val)
        return x
    return inner

Now consider:

f1 = outer()
f2 = outer()

print(f1(10))  # P
print(f1(20))  # Q
print(f2(30))  # R
print(f1(40))  # S

What will be the output of $\verb|P|$, $\verb|Q|$, $\verb|R|$, and $\verb|S|$?

  1. Output at line $\verb|Q|$ is $[10,20]$.
     
  2. $\verb|f1|$ and $\verb|f2|$ share the same list.
     
  3. Output at line $\verb|S|$ is $[10,20,40]$.
     
  4. Output at line $\verb|R|$ is $[10,20,30]$.

1 Answer

1 1 vote

Answer: (A) Output at line Q is and (C) Output at line S is

When outer() is called, a new local variable x (an empty list) is created each time.

  • f1 and f2 are two separate instances of the inner function, each with its own closure over a distinct x list created by their respective calls to outer().
  • f1(10) appends 10 to f1's list x, so P is [10].
  • f1(20) appends 20 to the same f1 list x, so Q is [10, 20].
  • f2(30) appends 30 to f2's separate list x, so R is [30].
  • f1(40) appends 40 to the same f1 list x, so S is [10, 20, 40].

Based on this, options A and C are correct statements. Option B is incorrect because f1 and f2 have separate lists. Option D is incorrect because R's output is [30].

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