Python · Theory

isalnum()

Theory

218/268

isalnum()

isalnum 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.

isalnum() — output — True then False. Space is not alnum.

Fresher trap: writing s.isalnum() and expecting s to update. Strings are immutable. Write s = s.isalnum(...) if you need the new value (when it returns a string).

Exam tip

Call isalnum on one real word and say what prints.

Example

# isalnum()
print("Asha12".isalnum())
print("Asha 12".isalnum())

isalnum() — output: True then False. Space is not alnum.

Short notes

Defisalnum works on str.
Ruleisalnum usually returns a new string.
Trapisalnum does not change the original string in place.

Python · Theory

isalnum()

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Theory

218/268

isalnum()

isalnum 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.

isalnum() — output — True then False. Space is not alnum.

Fresher trap: writing s.isalnum() and expecting s to update. Strings are immutable. Write s = s.isalnum(...) if you need the new value (when it returns a string).

Exam tip

Call isalnum on one real word and say what prints.

Example

# isalnum()
print("Asha12".isalnum())
print("Asha 12".isalnum())

isalnum() — output: True then False. Space is not alnum.

Short notes

Defisalnum works on str.
Ruleisalnum usually returns a new string.
Trapisalnum does not change the original string in place.

isalnum()

Example

Short notes

Questions

isalnum()

Example

Short notes

Questions