Struct num::BigUint

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pub struct BigUint { /* private fields */ }

Expand description

A big unsigned integer type.

Implementations§

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impl BigUint

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Creates and initializes a BigUint.

The bytes are in big-endian byte order.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from_bytes_be(b"A"),
           BigUint::parse_bytes(b"65", 10).unwrap());
assert_eq!(BigUint::from_bytes_be(b"AA"),
           BigUint::parse_bytes(b"16705", 10).unwrap());
assert_eq!(BigUint::from_bytes_be(b"AB"),
           BigUint::parse_bytes(b"16706", 10).unwrap());
assert_eq!(BigUint::from_bytes_be(b"Hello world!"),
           BigUint::parse_bytes(b"22405534230753963835153736737", 10).unwrap());

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pub fn from_bytes_le(bytes: &[u8]) -> BigUint

Creates and initializes a BigUint.

use num_bigint::{BigUint};

let inbase190 = &[14, 12, 125, 33, 15];
let a = BigUint::from_radix_be(inbase190, 190).unwrap();
assert_eq!(a.to_radix_be(190), inbase190);

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pub fn to_bytes_be(&self) -> Vec<u8>

Returns the byte representation of the BigUint in big-endian byte order.

§Examples

use num_bigint::BigUint;

let i = BigUint::parse_bytes(b"1125", 10).unwrap();
assert_eq!(i.to_bytes_be(), vec![4, 101]);

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pub fn to_bytes_le(&self) -> Vec<u8>

Returns the byte representation of the BigUint in little-endian byte order.

§Examples

use num_bigint::BigUint;

let i = BigUint::parse_bytes(b"1125", 10).unwrap();
assert_eq!(i.to_bytes_le(), vec![101, 4]);

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pub fn to_u32_digits(&self) -> Vec<u32>

Returns the u32 digits representation of the BigUint ordered least significant digit first.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from(1125u32).to_u32_digits(), vec![1125]);
assert_eq!(BigUint::from(4294967295u32).to_u32_digits(), vec![4294967295]);
assert_eq!(BigUint::from(4294967296u64).to_u32_digits(), vec![0, 1]);
assert_eq!(BigUint::from(112500000000u64).to_u32_digits(), vec![830850304, 26]);

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pub fn to_u64_digits(&self) -> Vec<u64>

Returns the u64 digits representation of the BigUint ordered least significant digit first.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from(1125u32).to_u64_digits(), vec![1125]);
assert_eq!(BigUint::from(4294967295u32).to_u64_digits(), vec![4294967295]);
assert_eq!(BigUint::from(4294967296u64).to_u64_digits(), vec![4294967296]);
assert_eq!(BigUint::from(112500000000u64).to_u64_digits(), vec![112500000000]);
assert_eq!(BigUint::from(1u128 << 64).to_u64_digits(), vec![0, 1]);

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pub fn iter_u32_digits(&self) -> U32Digits<'_> ⓘ

Returns an iterator of u32 digits representation of the BigUint ordered least significant digit first.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from(1125u32).iter_u32_digits().collect::<Vec<u32>>(), vec![1125]);
assert_eq!(BigUint::from(4294967295u32).iter_u32_digits().collect::<Vec<u32>>(), vec![4294967295]);
assert_eq!(BigUint::from(4294967296u64).iter_u32_digits().collect::<Vec<u32>>(), vec![0, 1]);
assert_eq!(BigUint::from(112500000000u64).iter_u32_digits().collect::<Vec<u32>>(), vec![830850304, 26]);

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pub fn iter_u64_digits(&self) -> U64Digits<'_> ⓘ

Returns an iterator of u64 digits representation of the BigUint ordered least significant digit first.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from(1125u32).iter_u64_digits().collect::<Vec<u64>>(), vec![1125]);
assert_eq!(BigUint::from(4294967295u32).iter_u64_digits().collect::<Vec<u64>>(), vec![4294967295]);
assert_eq!(BigUint::from(4294967296u64).iter_u64_digits().collect::<Vec<u64>>(), vec![4294967296]);
assert_eq!(BigUint::from(112500000000u64).iter_u64_digits().collect::<Vec<u64>>(), vec![112500000000]);
assert_eq!(BigUint::from(1u128 << 64).iter_u64_digits().collect::<Vec<u64>>(), vec![0, 1]);

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pub fn to_str_radix(&self, radix: u32) -> String

Returns the integer formatted as a string in the given radix. radix must be in the range 2...36.

§Examples

use num_bigint::BigUint;

let i = BigUint::parse_bytes(b"ff", 16).unwrap();
assert_eq!(i.to_str_radix(16), "ff");

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pub fn to_radix_be(&self, radix: u32) -> Vec<u8>

Returns the integer in the requested base in big-endian digit order. The output is not given in a human readable alphabet but as a zero based u8 number. radix must be in the range 2...256.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from(0xFFFFu64).to_radix_be(159),
           vec![2, 94, 27]);
// 0xFFFF = 65535 = 2*(159^2) + 94*159 + 27

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pub fn to_radix_le(&self, radix: u32) -> Vec<u8>

Returns the integer in the requested base in little-endian digit order. The output is not given in a human readable alphabet but as a zero based u8 number. radix must be in the range 2...256.

§Examples

use num_bigint::BigUint;

assert_eq!(BigUint::from(0xFFFFu64).to_radix_le(159),
           vec![27, 94, 2]);
// 0xFFFF = 65535 = 27 + 94*159 + 2*(159^2)

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pub fn bits(&self) -> u64

Determines the fewest bits necessary to express the BigUint.

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pub fn pow(&self, exponent: u32) -> BigUint

Returns self ^ exponent.

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pub fn modpow(&self, exponent: &BigUint, modulus: &BigUint) -> BigUint

Returns (self ^ exponent) % modulus.

Panics if the modulus is zero.

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pub fn modinv(&self, modulus: &BigUint) -> Option<BigUint>

Returns the modular multiplicative inverse if it exists, otherwise None.

This solves for x in the interval [0, modulus) such that self * x ≡ 1 (mod modulus). The solution exists if and only if gcd(self, modulus) == 1.

use num_bigint::BigUint;
use num_traits::{One, Zero};

let m = BigUint::from(383_u32);

// Trivial cases
assert_eq!(BigUint::zero().modinv(&m), None);
assert_eq!(BigUint::one().modinv(&m), Some(BigUint::one()));
let neg1 = &m - 1u32;
assert_eq!(neg1.modinv(&m), Some(neg1));

let a = BigUint::from(271_u32);
let x = a.modinv(&m).unwrap();
assert_eq!(x, BigUint::from(106_u32));
assert_eq!(x.modinv(&m).unwrap(), a);
assert!((a * x % m).is_one());