Length

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

Returns the length of the given string represented in number of bytes

namespace HH\Lib\Str;

function length(
  string $string,
): int;

This function is O(1): it always returns the number of bytes in the string, even if a byte is null. For example, Str\length("foo\0bar") is 7, not 3.

See Str\length_l() for the length in characters.

Guide

• String

Parameters

• string $string

Returns

• int

Examples

$result = Str\length("example_string");
echo($result);
//result: 14

$result = Str\length("");
echo($result);
//result: 0