Editing Happy number (section)

==Programming example==
The examples below implement the perfect digital invariant function for <math>p = 2</math> and a default base <math>b = 10</math> described in the definition of happy given at the top of this article, repeatedly; after each time, they check for both halt conditions: reaching 1, and [[Cycle detection|repeating a number]].

A simple test in [[Python (programming language)|Python]] to check if a number is happy:
<syntaxhighlight lang="python">
def pdi_function(number, base: int = 10):
    """Perfect digital invariant function."""
    total = 0
    while number > 0:
        total += pow(number % base, 2)
        number = number // base
    return total

def is_happy(number: int) -> bool:
    """Determine if the specified number is a happy number."""
    seen_numbers = set()
    while number > 1 and number not in seen_numbers:
        seen_numbers.add(number)
        number = pdi_function(number)
    return number == 1
</syntaxhighlight>