largeint

A library that supports large integer arithmetic.

Getting Started

First, add largeint to your dependencies:

[dependencies]
largeint = "0.2.0"

Next, add this to the root of your crate to bring the contents of largeint into the scope of your project:

extern crate largeint;

use largeint::largeint::*;

You can then easily create many instances of LargeInt:

let largeint1 = new(String::from("999999999999999999999"), Sign::Positive);
let largeint2 = new(String::from("999999999999999999999"), Sign::Negative);
let largeint3 = new(String::from("0"), Sign::Unsigned);

An instance of LargeInt contains two fields, the scalar value of the integer stored as a String and the sign of the integer stored as the enum, Sign, which can be Positive, Negative, or Unsigned (note that 0 is the only integer that should be assigned Unsigned).

Using new to create an instance of LargeInt is highly recommended as there are checks in place to ensure that the the instance of LargeInt will be created properly. For example, creating an instance of a LargeInt with a scalar value of 0 using new will automatically assign Sign::Unsigned to the sign of the LargeInt even if you enter another Sign variant.

The purpose of this library is to provide an easy-to-use large integer implementation in Rust. The ideal user is one that is looking to write small scale projects for personal use and does not want to spend a lot of time learning a complex crate such as num-bigint. For example, this library would be ideal for one looking to solve Project Euler Problem 13. However, the largeint library is not particularly efficient and therefore it is recommended to use a crate like num-bigint for more serious projects.

Let's see just how easy it is to start performing large integer arithmetic!

An Example

extern crate largeint;

use largeint::largeint::*;

fn main() {

    // Adding two LargeInts.
    let largeint1 = new(String::from("33901489213409093401849249010492000112"), Sign::Positive);
    let largeint2 = new(String::from("8294839402902010934029489031849310009324234230"), Sign::Negative);
    let largeint3 = largeint1.add(&largeint2);
    let largeint4 = new(String::from("8294839369000521720620395630000060998832234118"), Sign::Negative);
    assert_eq!(largeint3,largeint4);

    // Subtracting two LargeInts.
    let largeint1 = new(String::from("33901489213409093401849249010492000112"), Sign::Negative);
    let largeint2 = new(String::from("100320394280329423048093284093240234809833999"), Sign::Negative);
    let largeint3 = largeint1.sub(&largeint2);
    let largeint4 = new(String::from("100320360378840209638999882243991224317833887"), Sign::Positive);
    assert_eq!(largeint3,largeint4);

    // Multiplying two LargeInts.
    let largeint1 = new(String::from("239014892134090934018492404920112"), Sign::Negative);
    let largeint2 = new(String::from("820948948039443908494308943885"), Sign::Negative);
    let largeint3 = largeint1.mul(&largeint2);
    let largeint4 = new(String::from("196219024263243108752932957733805138559777844813650340515915120"), Sign::Positive);
    assert_eq!(largeint3,largeint4);

    // Dividing two LargeInts.
    let largeint1 = new(String::from("33901489213409093401849249010492088384894374938712"), Sign::Positive);
    let largeint2 = new(String::from("1003203942803294230480932840934343489333999"), Sign::Negative);
    let largeint3 = largeint1.div(&largeint2);
    let largeint4 = new(String::from("33793217"), Sign::Negative);
    assert_eq!(largeint3,largeint4);

    //The get_int() method returns the scalar value of the LargeInt as a String.
    println!("The value of largeint1 is: {}", largeint1.get_int());

    //The get_sign() method returns the Sign of the LargeInt as a String.
    println!("The Sign of largeint1 is: {}", largeint1.get_sign());
}

Updates

Code Breaking Changes: The subtraction method has been renamed sub from subtraction.

New Library Additions: Multiplication, floor division - and remainder - have been added.

License

This project is licensed under the MIT License - see LICENSE.md for more details.