php数组函数-array_pad()

array_pad()函数向一个数组插入带有指定值的指定数量的元素。

array_pad(array,size,value);

array：必需。规定数组

size：必需。指定的长度。正数则填补到右侧，负数则填补到则侧

value：必需。用来填补的值

注：如果设置了负的长度值，该函数会在原始数组之前插入新元素。

注：如果size参数小于原始数组的长度，该函数不会删除任何元素。

<?php
$a = array("Dog","Cat");
print_r(array_pad($a,5,0));
?>

输出：Array ( [0] => Dog [1] => Cat [2] => 0 [3] => 0 [4] => 0 )

带有负的size参数：

<?php
$a = array("Dog","Cat");
print_r(array_pad($a,-5,0));
?>

输出：Array ( [0] => 0 [1] => 0 [2] => 0 [3] => Dog [4] => Cat )

<?php
$a = array("Dog","Cat","Horse","Fish");
print_r(array_pad($a,3,0));
?>

输出：Array ( [0] => Dog [1] => Cat [2] => Horse [3] => Fish )