Concatenate First and Last Name into Full Name

1. The Challenge: Name Formatting

Create a function concat_name(first_name, last_name) that takes a first and last name and returns a single formatted string as "last_name, first_name".

2. Why It Matters

Formatting display names cleanly is standard requirement across user profiles, invoice PDF generators, and email notifications.

3. The Python Solution

Use Python f-strings (f"{last_name}, {first_name}"):

def concat_name(first_name, last_name):
    return f"{last_name}, {first_name}"

# Testing our function
print(concat_name("First", "Last"))   # Output: "Last, First"
print(concat_name("John", "Doe"))     # Output: "Doe, John"
print(concat_name("Mary", "Jane"))    # Output: "Jane, Mary"

4. Why f-Strings are Best Practice

Introduced in Python 3.6, f-strings (formatted string literals) are faster, cleaner, and less error-prone than legacy % formatting or " + " string concatenation.

5. Common Mistakes

• Wrong Order: Pay close attention to prompt requirements! Here the challenge requires "Last, First" order rather than "First Last".

6. Next Steps

Use f-strings for all string formatting. Next, let's calculate factorials in Python!