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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Operations and constants for `int`
pub use self::inst::pow;
mod inst {
pub type T = int;
pub const bits: uint = uint::bits;
/// Returns `base` raised to the power of `exponent`
pub fn pow(base: int, exponent: uint) -> int {
if exponent == 0u {
//Not mathemtically true if ~[base == 0]
return 1;
}
if base == 0 { return 0; }
let mut my_pow = exponent;
let mut acc = 1;
let mut multiplier = base;
while(my_pow > 0u) {
if my_pow % 2u == 1u {
acc *= multiplier;
}
my_pow /= 2u;
multiplier *= multiplier;
}
return acc;
}
#[test]
fn test_pow() {
assert (pow(0, 0u) == 1);
assert (pow(0, 1u) == 0);
assert (pow(0, 2u) == 0);
assert (pow(-1, 0u) == 1);
assert (pow(1, 0u) == 1);
assert (pow(-3, 2u) == 9);
assert (pow(-3, 3u) == -27);
assert (pow(4, 9u) == 262144);
}
#[test]
fn test_overflows() {
assert (max_value > 0);
assert (min_value <= 0);
assert (min_value + max_value + 1 == 0);
}
}
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