Struct IBig

Source

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

Expand description

An signed arbitrary precision integer.

This struct represents an arbitrarily large signed 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

There are four ways to create an IBig instance:

Use predifined constants (e.g. IBig::ZERO, IBig::NEG_ONE).
Use the literal macro ibig! defined in the dashu-macro crate.
Construct from a Sign and a UBig instance.
Parse from a string.

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

For printing, the IBig 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 = IBig::from(408580953453092208335085386466371u128);
let b = IBig::from(-0x1231abcd4134i64);
let c = IBig::from_str_radix("a2a123bbb127779cccc123", 32)?;
let d = IBig::from_str_radix("-1231abcd4134", 16)?;
assert_eq!(a, c);
assert_eq!(b, d);

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

§Memory

The internal representation of IBig is exactly the same as UBig. It just use a small trick to store the sign bit without additional memory allocation. This means that IBig also has the small integer optimization and the niche bit to use with simple enums.

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

Struct IBig Copy item path

§Parsing and printing

§Memory

Implementations§

impl IBig

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

§Examples

§Availability

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

§Examples

§Availability

impl IBig

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

§Examples

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

§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_ubig(&self) -> Option<&UBig>

§Examples

impl IBig

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

§Examples

§Panics

pub const fn is_multiple_of_const(&self, divisor: u128) -> bool

§Availability

impl IBig

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

§Panics

§Examples

impl IBig

pub const ZERO: IBig

pub const ONE: IBig

pub const NEG_ONE: IBig

pub fn as_sign_words(&self) -> (Sign, &[u64])

§Examples

pub const fn sign(&self) -> Sign

§Examples

pub fn into_parts(self) -> (Sign, UBig)

§Examples

pub fn from_parts(sign: Sign, magnitude: UBig) -> IBig

§Examples

pub const fn from_parts_const(sign: Sign, dword: u128) -> IBig

§Examples

pub const fn is_zero(&self) -> bool

§Examples

pub const fn is_one(&self) -> bool

§Examples

impl IBig

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

§Panics

§Examples

impl IBig

pub fn sqr(&self) -> UBig

§Examples

pub fn cubic(&self) -> IBig

§Examples

impl IBig

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

§Examples

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

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

§Examples

impl IBig

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

§Examples

impl IBig

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

§Examples

§Panics

impl IBig

pub const fn signum(&self) -> IBig

§Examples

Trait Implementations§

Struct IBig