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This is available as C\lastx in the www repository.

Returns the last element of the given Traversable, or throws if the Traversable is empty

namespace HH\Lib\C;

function lastx<T>(
  Traversable<T> $traversable,
): T;
  • For possibly empty Traversables, see C\last.
  • For single-element Traversables, see C\onlyx.

Time complexity: O(1) if $traversable is a Container, O(n) otherwise. Space complexity: O(1)



  • T


$strings = vec["a", "b", "c"];
$last_string = C\lastx($strings);
echo "Last string in traversable: $last_string \n";
//Output: Last string in traversable: c 

$empty_traversable = vec[];
$last_element = C\lastx($empty_traversable);
//Output: Hit a php exception : exception 'InvariantViolationException' with message
//'HH\Lib\C\lastx: Expected at least one element.'