array_fill(1, 5, 'apple')从索引1开始，填充5个apple

<?php
$a = array_fill(1, 5, 'apple');
print_r($a);
$b = array_fill(-2, 4, 'pear');
print_r($b);
输出：
Array
(
    [1] => apple
    [2] => apple
    [3] => apple
    [4] => apple
    [5] => apple
)
Array
(
    [-2] => pear
    [0] => pear
    [1] => pear
    [2] => pear
)