[TOC] ## 概述 固定长度的数组,超出则抛异常 ## 实例 ``` <?php $arr = new SplFixedArray(3); $arr[0]='a'; $arr[1]='a'; $arr[2]='a'; $arr[3]='a'; // Uncaught exception 'RuntimeException' with message 'Index invalid or out of range' //$arr[]='c';// Uncaught exception 'RuntimeException' with message 'Index invalid or out of range' ```