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slice

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 a substring of length $length of the given string starting at the $offset

namespace HH\Lib\Str;

function slice(
  string $string,
  int $offset,
  ?int $length = NULL,
): string;

If no length is given, the slice will contain the rest of the string. If the length is zero, the empty string will be returned. If the offset is out-of-bounds, a ViolationException will be thrown.

Previously known as substr in PHP.

Guide​

Parameters​

  • string $string
  • int $offset
  • ?int $length = NULL

Returns​

  • string

Examples​

$result = Str\slice("example_string", 5);
echo($result);
//result: "le_string"

$result = Str\slice("example_string", 5, 1);
echo($result);
//result: "l"

$result = Str\slice("example_string", 2, 0);
echo($result);
//result: ""

$result = Str\slice("example_string", 1000);
echo($result);
//result: <Throws exception>