Python Snippet 1: More Uses For Else

Python's else statement is pretty versatile and can be used with more than just if conditionals. You can also use else with for and while loops, and also as part of a try / except block.

In the case of for and while loops, the else block executes if the main loop wasn't terminated by either a break statement, or an exception.

In the the case of try / except, the else block runs in the event that an exception wasn't encountered as part of the try block.

# Print whether or a not an integer is prime for all integers from 2 to 100
for dividend in range(2,101):
    divisor = 2

    while dividend >= divisor ** 2:
        result = dividend / divisor
        if result.is_integer():
            print(f"{dividend} is not prime")
            # Break the while loop when a number is proven non-prime
      break
        divisor += 1

  # The else block runs if no break was encountered in the while loop
    else:
        print(f"{dividend} is prime")

"""
Convert the user input to an integer value and check the user's age is
over 18 if the conversion is successful. Otherwise, print an error message.
"""
try:
    age = int(input("Enter your age: "))
except:
    print ("Please only enter numerical characters.")

# The else block only runs if no exception gets raised
else:
    if age < 18:
        print("Sorry, you're too young to watch this movie.")
    else:
        print("Enjoy the movie!")

You can read more about using else statements with loops in the official docs.

Also, check out our next Python Snippet 2: Quick Sequence Reversal!