The isalnum()
method in Python is used to check whether a string contains only alphanumeric characters. It returns True
if all the characters in the string are alphanumeric, meaning they are either letters (a-z, A-Z) or digits (0-9). Otherwise, it returns False
.
Here's the syntax of the isalnum()
method:
string.isalnum()
# Examples of isalnum() method
string1 = "Hello123"
string2 = "Hello, world!"
string3 = "12345"
result1 = string1.isalnum()
result2 = string2.isalnum()
result3 = string3.isalnum()
print("String 1:", string1)
print("String 2:", string2)
print("String 3:", string3)
print("isalnum() result for String 1:", result1)
print("isalnum() result for String 2:", result2)
print("isalnum() result for String 3:", result3)
String 1: Hello123
String 2: Hello, world!
String 3: 12345
isalnum() result for String 1: True
isalnum() result for String 2: False
isalnum() result for String 3: True
In this example, string1
contains alphanumeric characters only ("Hello123"), so isalnum()
returns True
. string2
contains a space and punctuation marks, so it is not composed of only alphanumeric characters, and thus isalnum()
returns False
. string3
contains only digits ("12345"), so isalnum()
returns True
.
The isalnum()
method can be used to validate user input, check if a string contains only letters and digits, or to perform basic input validation for certain applications.