Python - Check if a String is Alphanumeric

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In Python, we can use the string'sisalnum()method to determine whether a string contains only letters and digits. If all characters in the string are letters or digits, it returnsTrue, otherwise it returnsFalse。

Example

def is_alphanumeric(s):
    return s.isalnum()

# Test
test_string1 = "Hello123"
test_string2 = "Hello 123"
test_string3 = "Hello@123"

print(is_alphanumeric(test_string1))  # Outputs True
print(is_alphanumeric(test_string2))  # Outputs False
print(is_alphanumeric(test_string3))  # Outputs False

Code explanation:

  • is_alphanumeric(s)The function accepts a stringsas a parameter.
  • s.isalnum()is a built-in method of strings, used to check whether a string contains only letters and digits.
  • If the stringscontains only letters and digits,isalnum()returnsTrue, otherwise it returnsFalse。
  • We tested three different strings:"Hello123"、"Hello 123"and"Hello@123", and output whether each is an alphanumeric string.

Output result:

True
False
False

Document 对象参考手册Python3 Examples

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