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length

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​

Parameters​

  • string $string

Returns​

  • int

Examples​

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

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