Miscellaneous Code Examples

Perfect Numbers

A perfect number is an integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number itself. For instance, 6 has proper divisors 1, 2, and 3, and 1 + 2 + 3 = 6, so 6 is a perfect number. The next perfect number is 28, because 1 + 2 + 4 + 7 + 14 = 28.

We can create a function to determine if a number is perfect or not. Add up all the factors of the number, and if the sum of all factors is equal to the number, then return true.

#import "Basic";

is_perfect :: (n: int) -> bool {
    if n <= 1 return false;

    sum := 1;
    for i: 2..n/2 + 1 {
        if n % i == 0 {
            sum += i;
        }
    }

    return sum == n;
}

main :: () {
    for i: 1..10000 {
        if is_perfect(i) {
            print("% is a perfect number.\n", i);
        }
    }
}

XOR Swap

The XOR swap is an algorithm that uses the XOR bitwise operation to swap the values of two variables without using the temporary variable which is normally required.

#import "Basic";

main :: () {
    a := 5;
    b := 9;

    print("Before swap: a = %, b = %\n", a, b);

    // XOR swap
    a = a ^ b;
    b = a ^ b;
    a = a ^ b;

    print("After swap:  a = %, b = %\n", a, b);
}