How to modify the absolute path of php (three methods)

In the process of developing websites or applications using PHP, we often need to reference external files or resources. At this time, you need to use absolute paths to ensure the correctness of the code. However, sometimes our absolute path needs to be changed. For example, when our website is transferred from a local server to a remote server, or when the file storage location is changed, the absolute path needs to be modified accordingly.

The following will introduce how to modify the absolute path of PHP.

1. Get the path of the current file

Before modifying the absolute path, we need to get the absolute path of the current file. You can use the following PHP code to get the path of the current file:

$dir = dirname(__FILE__);

Among them, the dirname() function is used to remove the path information in the file name, and the __FILE__ constant is used to get the full path of the current file. After executing the above code, the $dir variable is the path of the current file.

2. Modify the absolute path

After obtaining the path of the current file, we can modify the absolute path in a targeted manner. The specific method is as follows:

1. Manually modify the path

Manually modifying the absolute path is the simplest and least recommended method. We just need to change the original path to the new path. For example, our previous absolute path was:

/home/wwwroot/example.com/inc/config.php

Now we need to move this file to:

/home/wwwroot/newsite.com/inc/config.php

We need to change the original code that referenced the file:

require_once "/home/wwwroot/example.com/inc/config.php";

to :

require_once "/home/wwwroot/newsite.com/inc/config.php";

The problem with this method is that if there are many paths, or our website is referenced in multiple places, it will require a lot of code modifications, which is very cumbersome. Moreover, if we forget to modify the path somewhere, it will cause errors in the code.

2. Use relative paths

Compared with manually modifying paths, using relative paths is more convenient. We can convert the absolute path to a relative path so that even if the file is moved to another location, the path will not be wrong.

Taking the example at the beginning of this article as an example, we can convert the absolute path to a relative path through the following method:

$cur_path = dirname(__FILE__);
$target_path = '/home/wwwroot/newsite.com/inc/config.php';
$rel_path = str_replace($cur_path, '', $target_path);
if ($rel_path[0] == '/') {
    $rel_path = substr($rel_path, 1);
}

This code will calculate the position of $config_file relative to the current file. $rel_path is a relative path, we only need to use $rel_path to reference the file.

The advantage of this method is that even if the location of the file or the directory structure of the website is changed, the code can still run normally.

3. Use constants

If our website uses the same path in multiple places, in order to make it easier to modify the absolute path, we can use constants instead of the path. A constant is a fixed value in PHP that does not change throughout the execution of the script.

The method of defining constants is very simple, just use the define() function:

define('ROOT_PATH', '/home/wwwroot/newsite.com');

In this way, we can use the ROOT_PATH constant instead of the absolute path. For example, we need to reference the /config/config.php file. The original code that referenced the file was:

require_once "/home/wwwroot/newsite.com/config/config.php";

Now, we can change it to:

require_once ROOT_PATH . '/config/config.php';

In this way, even if we need to modify For absolute paths, you only need to modify the ROOT_PATH constant.

Summary

It is not difficult to modify the absolute path of PHP. We can achieve the goal by manually modifying it, using relative paths or using constants. However, for the sake of code maintainability and readability, we recommend using relative paths or constants instead of absolute paths. This way, the code will run normally even if the file location changes.

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