malachite_nz/integer/arithmetic/
is_power_of_2.rs

1// Copyright © 2026 Mikhail Hogrefe
2//
3// This file is part of Malachite.
4//
5// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
6// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
7// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
8
9use crate::integer::Integer;
10use malachite_base::num::arithmetic::traits::IsPowerOf2;
11
12impl IsPowerOf2 for Integer {
13    /// Determines whether an [`Integer`] is an integer power of 2.
14    ///
15    /// Negative values are never powers of 2.
16    ///
17    /// $f(x) = (\exists n \in \N : 2^n = x)$.
18    ///
19    /// # Worst-case complexity
20    /// $T(n) = O(n)$
21    ///
22    /// $M(n) = O(1)$
23    ///
24    /// where $T$ is time, $M$ is additional memory, and $n$ is `self.significant_bits()`.
25    ///
26    /// # Examples
27    /// ```
28    /// use core::str::FromStr;
29    /// use malachite_base::num::arithmetic::traits::{IsPowerOf2, Pow};
30    /// use malachite_base::num::basic::traits::Zero;
31    /// use malachite_nz::integer::Integer;
32    ///
33    /// assert_eq!(Integer::ZERO.is_power_of_2(), false);
34    /// assert_eq!(Integer::from(123).is_power_of_2(), false);
35    /// assert_eq!(Integer::from(0x80).is_power_of_2(), true);
36    /// assert_eq!(Integer::from(-0x80).is_power_of_2(), false);
37    /// assert_eq!(Integer::from(10).pow(12).is_power_of_2(), false);
38    /// assert_eq!(
39    ///     Integer::from_str("1099511627776").unwrap().is_power_of_2(),
40    ///     true
41    /// );
42    /// ```
43    #[inline]
44    fn is_power_of_2(&self) -> bool {
45        self.sign && self.abs.is_power_of_2()
46    }
47}
malachite_nz/integer/arithmetic/is_power_of_2.rs

malachite_nz/integer/arithmetic/
is_power_of_2.rs
