Return the First Element in a List

1. The Challenge: List Indexing

Create a function get_first_value(number_list) that takes a list containing numbers and returns the first element.

2. Why It Matters

Lists are Python's primary ordered collection data type. Accessing elements by 0-based index is an essential skill.

3. The Python Solution

Use zero-based index [0]:

def get_first_value(number_list):
    return number_list[0]

# Testing our function
print(get_first_value([1, 2, 3]))        # Output: 1
print(get_first_value([80, 5, 100]))      # Output: 80
print(get_first_value([-500, 0, 50]))     # Output: -500

4. Understanding Python List Indexing

• list[0]: First element.
• list[1]: Second element.
• list[-1]: Last element (negative indexing counts from the end!).

5. Common Mistakes

• IndexError on Empty Lists: Accessing list[0] on an empty list [] raises an uncaught IndexError: list index out of range. Handle empty lists safely: if not number_list: return None.

6. Next Steps

Use [0] for the first element and [-1] for the last element. Next, let's convert strings to integers and vice versa!