How to Convert Relative Paths to Absolute URLs in PHP?

Transforming Relative Paths into Absolute URLs in PHP

When working with URLs, it often becomes necessary to convert relative paths into absolute URLs. PHP provides a function called rel2abs that accomplishes this task.

Function Definition

function rel2abs($rel, $base)

• $rel: The relative path that needs to be converted.
• $base: The base URL from which the relative path will be resolved.

Usage Example

The following code snippet demonstrates how to use the rel2abs function:

$relativePath = 'images/logo.png';
$baseUrl = 'https://example.com';

$absoluteUrl = rel2abs($relativePath, $baseUrl);

echo $absoluteUrl; // Prints: https://example.com/images/logo.png

Implementation Details

The rel2abs function follows these steps to convert a relative path to an absolute URL:

1. If the relative path is already an absolute URL (i.e., it contains a scheme such as "http" or "https"), it is returned as is.
2. If the relative path starts with a query string ("?") or an anchor ("#"), it is appended to the base URL.
3. The base URL is parsed into its components (scheme, host, and path).
4. The non-directory element from the base URL's path is removed.
5. A "dirty" absolute URL is constructed by combining the base URL's host, modified path, and the relative path.
6. The "dirty" absolute URL is cleaned by removing any repeated slashes ("//"), unnecessary forward slashes after directory names ("/./"), or backtracking directory references ("/foo/../").
7. The final absolute URL is returned.

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