Expression operators

StoryBonsai expressions are built on the NCalc evaluator. This page lists every operator the manual promises to support. NCalc may accept additional grammar; treat anything not listed here as undocumented and subject to change.

Operators are grouped by kind below. Within each section, the operator is shown with its symbol and a short example. For function-style operators (Length(x), Min(a, b), etc.) see Expression functions.

Arithmetic

Addition

Adds two numbers, or joins text. When both operands are numbers, the result is the sum. If either operand is a string, the other side is converted to text and the two are joined with no space between them.

Symbol: +

1 + 2                         // 3
"hello, " + var_player_name   // "hello, Alice"
"score: " + var_hp            // "score: 42"

Subtraction

Subtracts the right operand from the left.

Symbol: -

5 - 2              // 3
var_hp - var_damage

Multiplication

Multiplies two numbers.

Symbol: *

3 * 4                        // 12
var_base_price * var_count

Division

Divides the left operand by the right. Result is a decimal for numeric inputs (no integer truncation).

Symbol: /

10 / 4                          // 2.5
var_total_cost / var_count

Modulo

Remainder after integer division.

Symbol: %

10 % 3                  // 1
var_turn_count % 2      // alternate-turn flag

Comparison

Equality

True when the operands are equal. String comparison is case-insensitive: "Apple" == "apple" is true.

Symbol: ==

var_score == 10
var_location == "tavern"

Inequality

True when the operands are not equal.

Symbol: !=

var_player_name != "Alice"
var_hp != 0

Greater than

True when the left operand is greater than the right.

Symbol: >

var_hp > 0
var_attempts > 3

Less than

True when the left operand is less than the right.

Symbol: <

var_level < 5
var_hunger < var_threshold

Greater than or equal

True when the left operand is greater than or equal to the right.

Symbol: >=

var_score >= 100
var_trust >= var_unlock_threshold

Less than or equal

True when the left operand is less than or equal to the right.

Symbol: <=

var_attempts <= 3
var_player_level <= var_scene_cap

Logical

Logical and

True when both operands are true. Also spelled and (case-insensitive).

Symbol: &&

var_has_key && var_door_closed
var_is_night and var_in_forest

Logical or

True when either operand is true. Also spelled or (case-insensitive).

Symbol: ||

var_helmet || var_shield
var_is_exhausted or var_is_injured

Logical not

True when the operand is false. Also spelled not (case-insensitive).

Symbol: !

!var_visited
not Played(node_intro)

Grouping

Parentheses

Parentheses control evaluation order. Standard precedence applies: multiplication and division bind tighter than addition and subtraction; comparison binds tighter than logical operators.

Symbol: ( )

(1 + 2) * 3                          // 9
(var_hp > 0) && (var_mp > var_cost)