Python Coding challenge - Day 594| What is the output of the following Python Code?

 

Code Explanation:

1. Function Definition

def func(val=[]):

This defines a function named func.

It takes one parameter: val.

The default value for val is an empty list [].

Important Note:

In Python, default argument values (like []) are evaluated only once, at the time the function is defined—not each time it's called.

This means that the same list is shared across multiple calls to the function if no new argument is provided.

2. Append to the List

    val.append(1)

This line adds the value 1 to the val list.

If val is the default list, this operation modifies the shared list.

3. Return the List

    return val

The modified list val is returned to the caller.

4. First Function Call

print(func())

Calls func() with no argument, so the default list [] is used.

1 is appended → the list becomes [1].

The list [1] is returned and printed.

Output at this point:

[1]

5. Second Function Call

print(func())

Again, func() is called without any argument, so it uses the same list as before (because it's the default list and mutable).

That list is now [1].

Another 1 is appended → the list becomes [1, 1].

The updated list [1, 1] is returned and printed.

Output at this point:

[1, 1]

Final Output

[1]

[1, 1]

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