Python Coding challenge - Day 578| What is the output of the following Python Code?

 Code Explanation:

1. Function Definition

def extend_list(val, list=None):

def is used to define a function named extend_list.

The function takes two parameters:

val: the value to be added to the list.

list: an optional parameter. If not provided, it defaults to None.

Using None as a default is a common Python practice to avoid mutable default arguments (like lists).

2. Handling the Default Argument

    if list is None:

        list = []

This block checks if list was provided.

If not (i.e., list is None), it creates a new empty list.

This ensures that a new list is created every time the function is called without an explicit list, avoiding shared state across calls.

3. Appending the Value

    list.append(val)

Adds the val to the list using the append() method.

This modifies the list in place.

4. Returning the Result

    return list

Returns the updated list containing the newly added value.

5. First Function Call

print(extend_list(10))

Calls extend_list with val = 10 and no list argument.

Since no list is provided, a new list is created: []

10 is appended: [10]

Output: "[10]"

6. Second Function Call

print(extend_list(20))

Calls extend_list again, this time with val = 20, still with no list argument.

Again, since no list is provided, a new empty list is created.

20 is appended: [20]

Output: "[20]"

Final Output:

[10]

[20]

Download Book - 500 Days Python Coding Challenges with Explanation