Python string isdecimal() method with example

The isdecimal() method is a built-in method in Python programming language for string handling.

This method checks whether the string contains only decimal characters (0-9). This means that it will return True if all characters in the string are decimals (i.e., from 0 to 9), otherwise it will return False.



How to use the isdecimal() method:

s = "123456"
print(s.isdecimal()) # This will output: True

s = "123456a"
print(s.isdecimal()) # This will output: False

s = "123.456"
print(s.isdecimal()) # This will output: False, because '.' is not a decimal character

Example 1

Validating User Input for Age.

age = input("Please enter your age: ")
if age.isdecimal():
  print("Thank you!")
  print("Invalid input. Please enter a valid age.")

Example 2

Validating a Zip/Postal Code.

def is_valid_zip(zip_code):
  if zip_code.isdecimal() and len(zip_code) == 5: # For a US ZIP code
    return True
    return False

print(is_valid_zip("12345")) # Outputs: True
print(is_valid_zip("12345abc")) # Outputs: False