The PHP code:

<?php
$array = array('blue', 'red', 'green', 'red');

$search = 'green';
$key = array_search($search, $array); // $key = 2;
echo "Array Search!  Found '$search' at array index $key in \$array.\n";
?>

Outputs:

Array Search! Found 'green' at array index 2 in $array.