Python Coding challenge - Day 496| What is the output of the following Python Code?

 

Code Explanation:

 Function Definition

def foo(x=[]):

What this does: Defines a function foo with one parameter x.

Default argument: The default value for x is an empty list [].

Important note: In Python, default arguments are evaluated only once when the function is defined, not each time it is called. This means that x will keep its state between calls if no new argument is passed.

 Function Body

    x.append(1)

Action: Appends the integer 1 to the list x.

So if x starts as [], it becomes [1] after one call, [1, 1] after two calls, etc.

    return x

Returns: The (now modified) list x.

First Function Call

print(foo())

No argument is passed → x uses the default value [].

x.append(1) → x becomes [1].

Returns [1], which is printed.

Second Function Call

print(foo())

Again, no argument is passed → it uses the same list from the previous call (not a fresh empty list).

x.append(1) → x becomes [1, 1].

Returns [1, 1], which is printed.

Output Summary

[1]

[1, 1]