Crate num_bigint

A Big integer (signed version: BigInt, unsigned version: BigUint).

A BigUint is represented as a vector of BigDigits. A BigInt is a combination of BigUint and Sign.

Common numerical operations are overloaded, so we can treat them the same way we treat other numbers.

Example

extern crate num_bigint;
extern crate num_traits;

use num_bigint::BigUint;
use num_traits::{Zero, One};
use std::mem::replace;

// Calculate large fibonacci numbers.
fn fib(n: usize) -> BigUint {
    let mut f0: BigUint = Zero::zero();
    let mut f1: BigUint = One::one();
    for _ in 0..n {
        let f2 = f0 + &f1;
        // This is a low cost way of swapping f0 with f1 and f1 with f2.
        f0 = replace(&mut f1, f2);
    }
    f0
}

// This is a very large number.
println!("fib(1000) = {}", fib(1000));

It’s easy to generate large random numbers:

extern crate rand;
extern crate num_bigint as bigint;

use bigint::{ToBigInt, RandBigInt};

let mut rng = rand::thread_rng();
let a = rng.gen_bigint(1000);

let low = -10000.to_bigint().unwrap();
let high = 10000.to_bigint().unwrap();
let b = rng.gen_bigint_range(&low, &high);

// Probably an even larger number.
println!("{}", a * b);

Compatibility

The num-bigint crate is tested for rustc 1.19 and greater.

Modules

big_digit

Structs

BigInt

A big signed integer type.

BigUint

A big unsigned integer type.

Enums

ParseBigIntError

Sign

A Sign is a BigInt’s composing element.

Constants

ZERO_BIG_DIGIT

Traits

RandBigInt

ToBigInt

A generic trait for converting a value to a BigInt.

ToBigUint

A generic trait for converting a value to a BigUint.

Type Aliases

BigDigit

A BigDigit is a BigUint’s composing element.

DoubleBigDigit

A DoubleBigDigit is the internal type used to do the computations. Its size is the double of the size of BigDigit.