rhaj/_archive/rhai_engine/rhaibook/language/num-op.md

Numeric Operators

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Numeric operators generally follow C styles.

Unary Operators

Operator	Description
+	positive
-	negative

let number = +42;

number = -5;

number = -5 - +5;

-(-42) == +42;      // two '-' equals '+'
                    // beware: '++' and '--' are reserved symbols

Binary Operators

Operator	Description	Result type	INT	FLOAT	[Decimal][rust_decimal]
+, +=	plus	numeric	yes	yes, also with INT	yes, also with INT
-, -=	minus	numeric	yes	yes, also with INT	yes, also with INT
*, *=	multiply	numeric	yes	yes, also with INT	yes, also with INT
/, /=	divide (integer division if acting on integer types)	numeric	yes	yes, also with INT	yes, also with INT
%, %=	modulo (remainder)	numeric	yes	yes, also with INT	yes, also with INT
**, **=	power/exponentiation	numeric	yes	yes, also FLOAT**INT	no
<<, <<=	left bit-shift (if negative number of bits, shift right instead)	numeric	yes	no	no
>>, >>=	right bit-shift (if negative number of bits, shift left instead)	numeric	yes	no	no
&, &=	bit-wise And	numeric	yes	no	no
|, |=	bit-wise Or	numeric	yes	no	no
^, ^=	bit-wise Xor	numeric	yes	no	no
==	equals to	bool	yes	yes, also with INT	yes, also with INT
!=	not equals to	bool	yes	yes, also with INT	yes, also with INT
>	greater than	bool	yes	yes, also with INT	yes, also with INT
>=	greater than or equals to	bool	yes	yes, also with INT	yes, also with INT
<	less than	bool	yes	yes, also with INT	yes, also with INT
<=	less than or equals to	bool	yes	yes, also with INT	yes, also with INT
..	exclusive range	[range]	yes	no	no
..=	inclusive range	[range]	yes	no	no

Examples

let x = (1 + 2) * (6 - 4) / 2;  // arithmetic, with parentheses

let reminder = 42 % 10;         // modulo

let power = 42 ** 2;            // power

let left_shifted = 42 << 3;     // left shift

let right_shifted = 42 >> 3;    // right shift

let bit_op = 42 | 99;           // bit masking

Floating-Point Interoperates with Integers

When one of the operands to a binary arithmetic [operator] is floating-point, it works with INT for the other operand and the result is floating-point.

let x = 41.0 + 1;               // 'FLOAT' + 'INT'

type_of(x) == "f64";            // result is 'FLOAT'

let x = 21 * 2.0;               // 'FLOAT' * 'INT'

type_of(x) == "f64";

(x == 42) == true;              // 'FLOAT' == 'INT'

(10 < x) == true;               // 'INT' < 'FLOAT'

Decimal Interoperates with Integers

When one of the operands to a binary arithmetic [operator] is [Decimal][rust_decimal], it works with INT for the other operand and the result is [Decimal][rust_decimal].

let d = parse_decimal("2");

let x = d + 1;                  // 'Decimal' + 'INT'

type_of(x) == "decimal";        // result is 'Decimal'

let x = 21 * d;                 // 'Decimal' * 'INT'

type_of(x) == "decimal";

(x == 42) == true;              // 'Decimal' == 'INT'

(10 < x) == true;               // 'INT' < 'Decimal'

Unary Before Binary

In Rhai, unary operators take [precedence] over binary operators. This is especially important to remember when handling operators such as ** which in some languages bind tighter than the unary - operator.

-2 + 2 == 0;

-2 - 2 == -4;

-2 * 2 == -4;

-2 / 2 == -1;

-2 % 2 == 0;

-2 ** 2 = 4;            // means: (-2) ** 2
                        // in some languages this means: -(2 ** 2)