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# Python3.x Python3 isalnum() Method [ Python3 Strings](#) * * * ## Description The `isalnum()` method is used to check whether a string consists of only alphanumeric characters, meaning all characters in the string are letters or numbers. * **Empty String**: If the string is empty (length 0), it returns `False`, because an empty string contains no letters or numbers. * **Case Sensitivity**: The `isalnum()` method is case-sensitive, meaning only characters that are letters or numbers are considered valid. * **Special Characters**: Special characters (such as punctuation, spaces, special symbols, etc.) are not considered letters or numbers. ## Syntax The syntax for the `isalnum()` method is: str.isalnum() ## Parameters * None. ## Return Value Returns `True` if the string has at least one character and all characters are alphanumeric; otherwise, returns `False`. ## Examples The following examples demonstrate the use of the `isalnum()` method: ## Example (Python 2.0+) #!/usr/bin/python3 str = "tutorial2016"# String has no spaces print(str.isalnum())str = "www."print(str.isalnum()) The output of the above example is: TrueFalse More examples: ## Example # Example 1: String containing letters and numbers print("abc123".isalnum())# Output: True # Example 2: String containing a space print("abc 123".isalnum())# Output: False # Example 3: String containing a special character print("abc#123".isalnum())# Output: False # Example 4: Empty string print("".isalnum())# Output: False # Example 5: String containing only numbers print("123456".isalnum())# Output: True # Example 6: String containing only letters print("abcdef".isalnum())# Output: True # Example 7: String containing an underscore (not a letter or number) print("abc_def".isalnum())# Output: False * * Python3 Strings](#)