Macro dec 

macro_rules! dec {
    ($($amount:tt)+) => { ... };
}

Creates a Decimal value from a numeric literal.

This is a compile-time checked macro — invalid literals produce a compile error, not a panic. rust_decimal does not need to be a direct dependency of the caller’s crate.

From rust_decimal_macros:

Any Rust number format works, for example:

use moneylib::dec;

let _ = dec!(1);          // plain positive integer
let _ = dec!(-1);         // plain negative integer
let _ = dec!(1_999);      // underscore as digit separator (readability)
let _ = dec!(- 1_999);    // negative with space before value

let _ = dec!(0b1);        // binary literal (base 2)
let _ = dec!(-0b1_1111);  // negative binary with separator (= -31)
let _ = dec!(0o1);        // octal literal (base 8)
let _ = dec!(-0o1_777);   // negative octal with separator (= -1023)
let _ = dec!(0x1);        // hexadecimal literal (base 16)
let _ = dec!(-0x1_Ffff);  // negative hex with separator, mixed case digits (= -131071)

let _ = dec!(1.);         // decimal point with no fractional digits
let _ = dec!(-1.111_009); // negative decimal with underscore separator in fraction
let _ = dec!(1e6);        // scientific notation: 1 × 10⁶ = 1_000_000
let _ = dec!(-1.2e+6);    // negative scientific notation with explicit '+' exponent
let _ = dec!(12e-6);      // scientific notation with negative exponent: 0.000_012
let _ = dec!(-1.2e-6);    // negative value with negative exponent: -0.000_001_2

Option radix

You can give it integers (not float-like) in any radix from 2 to 36 inclusive, using the letters too:

use moneylib::dec;

assert_eq!(dec!(100, radix 2),      dec!(4));      // "100" in base 2  = 1×4 = 4
assert_eq!(dec!(-1_222, radix 3),   dec!(-53));    // "1222" in base 3 = 27+18+6+2 = 53
assert_eq!(dec!(z1, radix 36),      dec!(1261));   // "z1"  in base 36 = 35×36+1 = 1261
assert_eq!(dec!(-1_xyz, radix 36),  dec!(-90683)); // "1xyz" in base 36, letters count as digit values 10–35

Option exp

This is the same as the e 10’s exponent in float syntax (except as a Rust expression it doesn’t accept a unary +.) You need this for other radixes. Currently, it must be between -28 and +28 inclusive:

use moneylib::dec;

assert_eq!(dec!(10, radix 2, exp 5),        dec!(200_000)); // "10" in base 2 = 2, then ×10⁵ = 200_000
assert_eq!(dec!(-1_777, exp -3, radix 8),   dec!(-1.023)); // "1777" in base 8 = 1023, then ×10⁻³ = -1.023

Examples

use moneylib::macros::dec;

let d = dec!(2.51);
assert_eq!(d.to_string(), "2.51");