(PHP 5 >= 5.3.0, PHP 7, PHP 8)
SplFixedArray::setSize — Change the size of an array
$size): bool
   Change the size of an array to the new size of size. If 
   size is less than the current array size, any values after the new size 
   will be discarded. If size is greater than the current array size, the 
   array will be padded with null values.
  
size
       The new array size. This should be a value between 0 and PHP_INT_MAX.
      
   成功时返回 true, 或者在失败时返回 false。
  
   Throws InvalidArgumentException when size is less than zero.
  
   Raises E_WARNING when size cannot be used as a number.
  
示例 #1 SplFixedArray::setSize() example
<?php
   $array = new SplFixedArray(5);
   echo $array->getSize()."\n";
   $array->setSize(10);
   echo $array->getSize()."\n";
?>
以上例程会输出:
5 10