Python3 isalnum() method

Python3 字符串Python3 Strings

Description

The isalnum() method is used to check whether a string consists of letters and numbers, that is, all characters in the string are letters or numbers.

  • Empty string: If the string is empty (length is 0), it returnsFalse, because an empty string contains no letters or numbers.
  • Case sensitivity：isalnum()The method is case-sensitive, meaning only characters that are letters or numbers are considered valid.
  • Special characters: Special characters (such as punctuation marks, spaces, special symbols, etc.) are not considered letters or numbers.

Syntax

isalnum() method syntax:

str.isalnum()

Parameters

  • None.

Return Value

If the string has at least one character and all characters are letters or numbers, it returns True; otherwise, it returns False.

Examples

The following example demonstrates the isalnum() method:

Example (Python 2.0+)

#!/usr/bin/python3 str = "example2016" # String without spaces print (str.isalnum()) str = "www.example.com" print (str.isalnum())

The output of the above example is as follows:

True
False

More examples:

Example

# Example 1: String containing letters and numbers
print("abc123".isalnum())  # Output: True

# Example 2: String containing spaces
print("abc 123".isalnum())  # Output: False

# Example 3: String containing special characters
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 underscore, which is not a letter or number
print("abc_def".isalnum())  # Output: False

Python3 字符串Python3 Strings

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