Python 3 reference · String Methods

Python String isalnum() Method

Return True if every character is a letter or a digit and the string isn't empty.

Syntax

str.isalnum()

True or False.

Letters and digits onlyTry it yourself

for s in ["abc123", "abc 123", "", "Ünïcode9"]:
    print(repr(s), s.isalnum())

Output

'abc123' True
'abc 123' False
'' False
'Ünïcode9' True

Allow some extra charactersTry it yourself

username = "ada_l"
print(username.replace("_", "").isalnum())

Output

True

Version	Change
Python 3.0	Added

str.isalpha() · Return True if every character is a letter (in any alphabet) and the string isn't empty. Spaces and digits return False.
str.isdigit() · Return True if every character is a digit, including superscripts like ². Signs, spaces and decimal points return False.
str.isidentifier() · Return True if the string is a valid Python identifier: a name you could use for a variable, function or class.
Python Strings · tutorial