Struct UBig

Source

pub struct UBig(/* private fields */);

Expand description

An unsigned arbitrary precision integer.

This struct represents an arbitrarily large unsigned integer. Technically the size of the integer is bounded by the memory size, but it’s enough for practical use on modern devices.

§Parsing and printing

To create a UBig instance, there are three ways:

Use predifined constants (e.g. UBig::ZERO, UBig::ONE).
Use the literal macro ubig! defined in the dashu-macro crate.
Parse from a string.

Parsing from either literal or string supports representation with base 2~36.

For printing, the UBig type supports common formatting traits (Display, Debug, LowerHex, etc.). Specially, printing huge number using Debug will conveniently omit the middle digits of the number, only print the least and most significant (decimal) digits.

// parsing
let a = UBig::from(408580953453092208335085386466371u128);
let b = UBig::from(0x1231abcd4134u64);
let c = UBig::from_str_radix("a2a123bbb127779cccc123", 32)?;
let d = UBig::from_str_radix("1231abcd4134", 16)?;
assert_eq!(a, c);
assert_eq!(b, d);

// printing
assert_eq!(format!("{}", UBig::from(12u8)), "12");
assert_eq!(format!("{:#X}", UBig::from(0xabcdu16)), "0xABCD");
if Word::BITS == 64 {
    // number of digits to display depends on the word size
    assert_eq!(
        format!("{:?}", UBig::ONE << 1000),
        "1071508607186267320..4386837205668069376"
    );
}

§Memory

Integers that fit in a DoubleWord will be inlined on stack and no heap allocation will be invoked. For large integers, they will be represented as an array of Words, and stored on heap.

Note that the UBig struct has a niche bit, therefore it can be used within simple enums with no memory overhead.

use core::mem::size_of;
assert_eq!(size_of::<UBig>(), size_of::<Option<UBig>>());

Struct UBigCopy item path

§Parsing and printing

§Memory

Implementations§

impl UBig

pub fn set_bit(&mut self, n: usize)

§Examples

pub fn clear_bit(&mut self, n: usize)

§Examples

pub const fn trailing_zeros(&self) -> Option<usize>

§Examples

§Availability

pub const fn trailing_ones(&self) -> Option<usize>

§Examples

§Availability

pub fn split_bits(self, n: usize) -> (UBig, UBig)

§Examples

pub fn clear_high_bits(&mut self, n: usize)

§Examples

pub fn count_ones(&self) -> usize

§Examples

pub fn count_zeros(&self) -> Option<usize>

§Examples

impl UBig

pub fn from_le_bytes(bytes: &[u8]) -> UBig

§Examples

pub fn from_be_bytes(bytes: &[u8]) -> UBig

§Examples

pub fn to_le_bytes(&self) -> Box<[u8]>

§Examples

pub fn to_be_bytes(&self) -> Box<[u8]>

§Examples

pub fn to_f32(&self) -> Approximation<f32, Sign>

§Examples

pub fn to_f64(&self) -> Approximation<f64, Sign>

§Examples

pub const fn as_ibig(&self) -> &IBig

§Examples

impl UBig

pub fn is_multiple_of(&self, divisor: &Self) -> bool

§Examples

§Panics

pub const fn is_multiple_of_const(&self, divisor: DoubleWord) -> bool

§Availability

impl UBig

pub fn in_radix(&self, radix: u32) -> InRadix<'_>

§Panics

§Examples

impl UBig

pub fn ilog(&self, base: &UBig) -> usize

§Panics

§Examples

impl UBig

pub fn sqr(&self) -> UBig

§Examples

pub fn cubic(&self) -> UBig

§Examples

impl UBig

pub fn from_str_radix(src: &str, radix: u32) -> Result<UBig, ParseError>

§Examples

pub fn from_str_with_radix_prefix(src: &str) -> Result<(UBig, u32), ParseError>

pub fn from_str_with_radix_default( src: &str, default_radix: u32, ) -> Result<(UBig, u32), ParseError>

§Examples

impl UBig

pub fn pow(&self, exp: usize) -> UBig

§Examples

impl UBig

pub fn remove(&mut self, factor: &UBig) -> Option<usize>

impl UBig

pub fn nth_root(&self, n: usize) -> UBig

§Examples

§Panics

impl UBig

pub const ZERO: Self

pub const ONE: Self

pub fn as_words(&self) -> &[Word] ⓘ

§Examples

pub const fn from_word(word: Word) -> Self

§Examples

pub const fn from_dword(dword: DoubleWord) -> Self

Struct UBig