dict.setdefault() — Python Technical Interview Questions & Answers

dict.setdefault()

dict.setdefault()

  • dict.setdefault() works on a dictionary — labelled data like marks["Asha"] = 90. Keys map to values. Loop with .items() when you need both.
  • dict.setdefault() — output: 90, then 0, then {'Asha': 90, 'Neha': 0}. setdefault adds only if missing.
  • Trap for dict.setdefault(): writing d[missing] in a viva. Prefer get when the key might not exist.
  { "Asha": 90, "Ravi": 85 }
         │           │
        key        value

Technical Interview Tip: get vs [] — one sentence + tiny dict of marks.

Code Examples for dict.setdefault()

Example

# dict.setdefault()
d = {"Asha": 90}
print(d.setdefault("Asha", 0))
print(d.setdefault("Neha", 0))
print(d)

dict.setdefault() — output: 90, then 0, then {'Asha': 90, 'Neha': 0}. setdefault adds only if missing.

How to Explain dict.setdefault() to an Interviewer

Explain dict.setdefault() as if you are teaching a junior — definition, then one tiny script.

dict.setdefault() works on a dictionary. dict.setdefault() — get when key may miss.

What does the example print, and why?

dict

What mistake do freshers make with dict.setdefault()?

dict.setdefault() — d[missing] → KeyError.