@lang:len

Length of a value: element count for an array, byte length for a string or bytes.

Returns: number

Syntax

@lang:len(value)

Arguments

Name	Type	Description
value	array	Source array, string or bytes value

See Also

• @at — access element by index
• @slice — extract a sub-array
• @str.len — string length

On-chain face (@len!)

The decoded length of the dynamic return value of a call, on-chain: element count for arrays, byte length for string/bytes.

Examples

load lang

set $gov 0xc0dbDcA66a0636236fAbe1B3C16B1bD4C84bB1E1

# Top level: compiles to a core nav ending in the LEN sentinel
assert @len!($gov::{voters()(address[])}) >= 3 "not enough voters"
assert @len!($gov::{voters()(address[])}) != 0

# Nested: the same LEN-sentinel nav, composable as a number
assert @num!(@len!($gov::{voters()(address[])}) * 2) > 4

Notes

• For a string/bytes return the decoded length is the byte length (UTF-8 characters may span multiple bytes). For raw returndata size use @bytes.len!.
• Over a NESTED ARRAY FACE (@len!(@filter!(…)), @len!(@safe:owners!())) the length is the live ELEMENT COUNT of the words payload (its byte length over 32); byte lengths of string/bytes faces stay with @bytes.len!/@str.len!.

See Also

• assert, @bytes.len!