Python string Method - isalnum()

The isalnum() method is a built-in Python string method that returns a boolean value indicating whether all the characters in the string are alphanumeric (i.e., either letters or digits).

Here's an example that demonstrates the usage of the isalnum() method:

string1 = "Hello123"
string2 = "Hello, world!"

print(string1.isalnum())  # Output: True
print(string2.isalnum())  # Output: False

In this example, we create two strings: string1 which contains alphanumeric characters only, and string2 which contains a non-alphanumeric character. We then call the isalnum() method on each string. The method returns True for string1 since all its characters are alphanumeric, and False for string2 since it contains a non-alphanumeric character.

The isalnum() method returns True if the string is not empty and all its characters are alphanumeric, and False otherwise. Here are some additional examples:

print("".isalnum())  # Output: False
print("123".isalnum())  # Output: True
print("Hello, world!".isalnum())  # Output: False

In the first example, we call the isalnum() method on an empty string, which returns False since the string is not alphanumeric. In the second example, we call the method on a string containing only digits, which returns True. In the third example, we call the method on a string that contains non-alphanumeric characters, which returns False.