来看下面的例子，array_fill()函数——填充数组函数：
运行结果：
array([0] => array([0] => a[1] => b[2] => c[3] => d)
[1] => array([0] => a[1] => b[2] => c[3] => d)
[2] => array([0] => a[1] => b[2] => c[3] => d)
[3] => array([0] => a[1] => b[2] => c[3] => d)
[4] => array([0] => a[1] => b[2] => c[3] => d)
)array([string] => testing[2] => testing[9] => testing[sdk] => testing[pk] => testing)