Functions in Python — Python Technical Interview Questions & Answers

Functions in Python

Functions in Python

  • A function is a reusable block that does one job. You write it once with def, then call it. square(5) should return 25 — not only print it, if the caller needs the number.
  • Shape: def square(n): return n * n. Colon, indented body. Call: print(square(5)). Output 25. Without return, the function gives None. Freshers print inside and wonder why x = square(5) is None.
  • Defaults: def greet(name="Guest"). Call greet() or greet("Asha"). Keep one job per function. Name it after what it does: total_marks, not do_stuff.
  • Let’s do it on the board. def square(n): return n * n. print(square(5)) → 25. Change to square(6) in your head → 36. That dry-run is the example.
  • Functions in Python — output: 25. square(5) returns 25. Change to square(6) → 36.
  def square(n):
      return n * n
         │ square(5)
         ▼
        25

Technical Interview Tip: Explain return vs no return.

Code Examples for Functions in Python

Example

# Functions
def square(n):
    return n * n

print(square(5))

Functions in Python — output: 25. square(5) returns 25. Change to square(6) → 36.

How to Explain Functions in Python to an Interviewer

Explain Functions as if you are teaching a junior — definition, then one tiny script.

A function is a reusable block that does one job. Shape: def square(n): return n * n.

What does the example print, and why?

Functions in Python — output: 25

What mistake do freshers make with Functions?

Defaults: def greet(name="Guest").