len()

The len() built-in function returns the length or size of a value. It works with arrays, strings, and objects.

Syntax

len(value)

Array length

Returns the number of elements in an array:

let arr = [10, 20, 30];
print(len(arr));      // 3

let empty = [];
print(len(empty));    // 0

String length

Returns the number of characters in a string:

let s = "hello";
print(len(s));        // 5

let empty = "";
print(len(empty));    // 0

Object field count

Returns the number of fields in an object:

class Point {
    let x = 10;
    let y = 20;
    let z = 30;
}

let p = new Point();
print(len(p));        // 3

Common use case

Iterating with index using len():

let arr = ["a", "b", "c"];

@unsafe for (let i = 0; i < len(arr); i = i + 1) {
    print("Index", i, ":", arr[i]);
}

Error handling

⚠️ Calling len() on unsupported types (like integers or booleans) throws a runtime error.