Last Updated : 21 Apr, 2025
The isalnum() method is a string function in Python that checks if all characters in the given string are alphanumeric. If every character is either a letter or a number, isalnum() returns True. Otherwise, it returns False.
For Example:
Python
s = "Python123"
res = s.isalnum()
print(res)
Explanation: In this example, s contains only letters and numbers, so isalnum() returns True.
Syntaxs.isalnum()
Parameters:
Return Type:
An empty string will return False since there are no alphanumeric characters.
Python
s = ""
res = s.isalnum()
print(res)
Example 2: String with Only Digits
The method will also return True for a string with only numeric characters.
Python
s = "123456"
res = s.isalnum()
print(res)
Example 3: String with Only Letters
Similarly, a string containing only letters will return True.
Python
s = "Python"
res = s.isalnum()
print(res)
Example 4: String with Non-Alphanumeric Characters
If the string contains a space and an exclamation mark, so isalnum() returns False.
Python
s = "Python 123!"
res = s.isalnum()
print(res)
Explanation: in this code, isalnum() returns False because the string s contains space " " and exclamation mark (!) which are neither numbers nor alphabets.
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