isdecimal() — Python Technical Interview Questions & Answers

isdecimal()

isdecimal()

  • isdecimal is a string helper. You call it on text like "Asha" or "banana". It gives a new string (or a number/True-False). The old string does not change unless you assign the result back.
  • isdecimal() — output: True then False. Decimal digits only.
  • Fresher trap: writing s.isdecimal() and expecting s to update. Strings are immutable. Write s = s.isdecimal(...) if you need the new value (when it returns a string).

Technical Interview Tip: Call isdecimal on one real word and say what prints.

Code Examples for isdecimal()

Example

# isdecimal()
print("21".isdecimal())
print("²".isdecimal())

isdecimal() — output: True then False. Decimal digits only.

How to Explain isdecimal() to an Interviewer

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

isdecimal works on str. isdecimal usually returns a new string.

What does the example print, and why?

isdecimal() — output: True then False

What mistake do freshers make with isdecimal()?

isdecimal does not change the original string in place.