php 数组首部添加元素

<?php
$array = array("apple", "banana");
$newLength = array_unshift($array, "orange", "grape");

print_r($array);
echo "New length: " . $newLength;
?>

Array
(
    [0] => orange
    [1] => grape
    [2] => apple
    [3] => banana
)
New length: 4

<?php
$array = array("apple", "banana");
if (!is_array($array)) {
    echo "The first argument must be an array.";
} else {
    $newLength = array_unshift($array, "orange", "grape");
    if ($newLength === false) {
        echo "Failed to unshift elements. Check memory allocation.";
    } else {
        print_r($array);
        echo "New length: " . $newLength;
    }
}
?>