Rumah >pembangunan bahagian belakang >tutorial php >PHP include文件包含路径搜索问题的总结
首先我们来看php官方手册中对include的文件搜索原则的描述:
Files for including are first looked for in each include_path entry relative to the current working directory, and then in the directory of current script. E.g. if your include_path is libraries , current working directory is , you included and there is include "b.php" in that file, is first looked in and then in . If filename begins with ./ or ../ , it is looked only in the current working directory.
寻找包含文件的顺序先是在当前工作目录的相对的 include_path 下寻找,然后是当前运行脚本所在目录相对的 include_path 下寻找。例如 include_path 是 . ,当前工作目录是 ,脚本中要 include 一个 并且在该文件中有一句 include "b.php" ,则寻找 的顺序先是 ,然后是 。如果文件名以 ./ 或者 ../ 开始,则只在当前工作目录相对的 include_path 下寻找。
所以如下所示的文件结构
----a.php
----include/b.php
----include/c.php
其中a.php
<?php include 'include/b.php'; ?> ----------------------- b.php <?php include 'c.php'; include 'include/c.php'; ?>
--------------------------
c.php
<?php echo 'c.php'; ?>
--------------------------
都能正确运行,说明b.php中两种不同包含路径都是可行的,根据include寻找包含文件的方式都能找到c.php。
但是最好的方式还是使用绝对路径,如果使用了绝对路径,php内核就直接通过路径去载入文件而不用去include path逐个搜索文件,增加了代码执行效率
<?php define('ROOT_PATH',dirname(FILE)); include ROOT_PATH.'/c.php'; ?>
不同的文件包含方式,程序的执行性能比较具体可以参照此文
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