Struct IOUNumber 

#[repr(C)]
pub struct IOUNumber(pub [u8; 8]);

The 8-byte value field of an XRPL fungible token (IOU) amount.

This is the leading 8 bytes of a serialized IOU STAmount (the value, without the trailing currency and issuer). It is not an STAmount, and it is a different encoding from the 12-byte STNumber used for host arithmetic.

The format is [Type:1][Sign:1][Exponent:8][Mantissa:54] bits, big-endian.

Important

This type is a read-only wire representation. Arithmetic MUST be performed through the host’s Number (STNumber) type, which uses rippled’s Number class to stay consensus-exact. The accessors below expose the raw encoded fields for inspection only.

Format Details

• Type bit (bit 63): Always 1 for fungible tokens
• Sign bit (bit 62): 1 = positive, 0 = negative
• Exponent (bits 61-54): 8 bits, biased by 97 (real exponent range -96 to +80)
• Mantissa (bits 53-0): 54 bits providing ~16 decimal digits precision

Special Values

• Zero: 0x8000000000000000 (mantissa is 0)
• Maximum: ~9.999999999999999 × 10^80
• Minimum positive: ~1.0 × 10^-81

Derived Traits

• PartialEq, Eq: Enable comparisons (bitwise comparison only)
• Debug, Clone: Standard traits for development and consistency

Note: PartialEq and Eq perform bitwise comparison only. For semantic comparison of amounts (e.g., handling different representations of zero), convert to Number and compare there.

Tuple Fields

0: [u8; 8]

Implementations

impl IOUNumber

pub fn is_positive(&self) -> bool

Returns true if the sign bit marks this value as positive.

Note the sign bit is meaningless for zero; prefer IOUNumber::is_zero to test for zero.

pub fn is_zero(&self) -> bool

Returns true if this value is zero (mantissa is 0).

pub fn exponent(&self) -> i32

Returns the real (unbiased) base-10 exponent.

WARNING: prefer the host Number type for arithmetic; this exposes the raw encoded field.

pub fn mantissa(&self) -> u64

Returns the 54-bit unsigned mantissa.

WARNING: prefer the host Number type for arithmetic; this exposes the raw encoded field.

Trait Implementations

impl Clone for IOUNumber

fn clone(&self) -> IOUNumber

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for IOUNumber

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for IOUNumber

impl From<[u8; 8]> for IOUNumber

fn from(value: [u8; 8]) -> Self

Converts to this type from the input type.

impl PartialEq for IOUNumber

fn eq(&self, other: &IOUNumber) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for IOUNumber