hphp/hack/manual/hsl/Functions/HH.Lib.C/find.md
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Returns the first value of the given Traversable for which the predicate returns true, or null if no such value is found
namespace HH\Lib\C;
function find<T>(
Traversable<T> $traversable,
(function(T): bool) $value_predicate,
): ?T;
Time complexity: O(n) Space complexity: O(1)
Traversable<T>$traversable(function(T): bool) $value_predicate?T$strings = vec["a", "b", "c", "d"];
$predicate_string_1 = C\find($strings, $x ==> $x == "b");
echo "First predicate: $predicate_string_1\n";
//Output: First predicate: b
$predicate_string_2 = C\find($strings, $x ==> $x == "z");
$predicate_string_2_as_string = $predicate_string_2 ?? "null";
echo "Second predicate: $predicate_string_2_as_string\n";
//Output: Second predicate: null
$repeat_strings = vec["a1", "b", "a2", "d"];
$predicate_string_3 = C\find($repeat_strings, $x ==> ($x == "a1" || $x == "a2"));
echo "Repeat_predicate: $predicate_string_3\n";
//Output: Repeat_predicate: a1