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contains

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 true if the given Traversable contains the value

namespace HH\Lib\C;

function contains<T1, T2>(
  Traversable<T1> $traversable,
  T2 $value,
): bool;

Strict equality is used.

Time complexity: O(n) (O(1) for keysets) Space complexity: O(1)

Parameters​

Returns​

  • bool

Examples​

$strings = vec["a", "b", "c", "d"];
$contains_result_1 = C\contains($strings, "a");
echo "First contains result: $contains_result_1\n";
//Output: First contains result: true

$contains_result_2 = C\contains($strings, "z");
echo "Second contains result: $contains_result_2\n";
//Output: Second contains result: false

$empty_strings = vec[];
$contains_result_3 = C\contains($empty_strings, "a");
echo "Third contains result: $contains_result_3\n";
//Output: Third contains result: false