Python Coding challenge - Day 513| What is the output of the following Python Code?

 

Code Explanation:

Function Definition

def tricky(a=[], b=0):

Defines a function tricky with:

a: A list with a default value of [] (mutable object).

b: An integer with a default value 0 (immutable object).

Key Point: The default list [] is created only once when the function is defined, not each time it's called. So a will retain its state between calls unless explicitly passed a new list.

Append b to a

    a.append(b)

Adds the current value of b to the list a.

On first call, a is empty: [], and b is 0, so after this: a = [0].

Increment b

    b += 1

Increases the value of b by 1.

Now b = 1.

Return Tuple

    return a, b

Returns a tuple: the updated list a and the incremented value of b.

First Call

print(tricky())

a is the default list [], b = 0.

a.append(0) → a = [0]

b += 1 → b = 1

Returns: ([0], 1)

Output:

([0], 1)

Second Call

print(tricky())

Here's the tricky part:

a is still [0] from the first call (because the default list is reused).

b = 0 again (default integer is recreated every time).

a.append(0) → a = [0, 0]

b += 1 → b = 1

Returns: ([0, 0], 1)

Output:

([0, 0], 1)

Final Output

([0], 1)

([0, 0], 1)