Detailed explanation of the usage of set_include_path and get_include_path

The article is reproduced from: http://blog.sina.com.cn/s/blog_4ce89f200100twbl.html

First of all, the set_include_path function dynamically modifies the include_path in PHP.ini in the script.
As for this include_path, it can be limited to the following include and require path ranges, or predefined.

is like:
If we don’t set this value, maybe we need to write some complete paths:

include("123/test1.php");

include("123/test3.php");
require( "123/test5.php");?>
to introduce many external files, but if we set set_include_path("123/"), we just You can use the following code instead.

set_include_path("123/");

include("test1. php");
include("test2.php"); include("test3.php");
require("test4.php");
?>
Because when an include or require operation is executed, the path specified by include_path will be searched for the file to be imported. Although I don’t know if this will optimize performance, but To be sure, some code can be saved. Haha~
So at the beginning, I thought it would be the same whether I added it or not, because I only included one file in this folder. Later, I finally discovered the mystery! What’s deplorable is that there isn’t an article like mine on the Internet…the same article is reposted over and over again.
So this function can not only define one folder, we can define many folders. As shown below, I want to write an initialization function:
function initialize(){
set_include_path(get_include_path().PATH_SEPARATOR ."core/");
set_include_path(get_include_path().PATH_SEPARATOR ."app/");
set_include_path(get_include_path().PATH_SEPARATOR ."admin/"); set_include_path(get_include_path(). PATH_SEPARATOR ."lib/");
set_include_path(get_include_path().PATH_SEPARATOR ."include/");
set_include_path(get_include_path().PATH_SEPARA TOR."data/");
set_include_path(get_include_path().PATH_SEPARATOR."cache/");
}
So its path becomes:
.;C:php5pear;core/ ;app/;admin/;lib/;include/;data/;cache/
Hey, we found that there is another one in front of us.;C:php5pear;What is going on? In fact, what if we Without writing, just output the default value of include_path, and you will find that it is.;C:php5pear; It allows you to go to any imported file.
If many more folders are loaded, we can just write the file name directly!
But just like my original question, why is our company’s code different from other people’s? It turns out that if I just write a __FILE__));
Then when I import files from other folders, an error will be reported saying that they cannot be found in the folder I specified. First, let’s output it in another way:


set_include_path(dirname( __FILE__));
$include_value = ini_get('include_path');
echo $include_value;
?>
The result is: D:AppServwww
include("test4.php");
But if I look for will Error report:
Warning: include() [
function.include]:Failed opening 'test1.php' for inclusion(include_path='D:AppServwww') inD:AppServwwwtest.phpon line6
And we also found that .;C:php5pear; has been replaced . So when we use it, if we do not only introduce files in one folder, we need to add get_include_path().PATH_SEPARATOR. get_include_path() is the default value to get the current include_path

PATH_SEPARATOR is a constant, It is the path demarcation of include, which is the same on window; on unix and Linux Is:Finally, I would like to say that we can also use another method: the most original one:

ini_set
( 'include_path', 'directory name');
If The required file cannot be found in the specified directory, and if a file with this name happens to exist in the current page directory, the file in the current directory will be imported by default.

When multiple directories are specified as include_path, and the files required to be included have files with the same name in these directories, PHP chooses to use the include_path setting. Files in the top directory. The above introduces the detailed usage of set_include_path and get_include_path, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.