How can PHP developers account for URLs that do not include "www" when validating user input?

When validating user input for URLs in PHP, developers can check if the input includes "www" or not by using regular expressions. If the input does not include "www", the developer can prepend it to the URL before further processing. This ensures that the URL is in a standardized format for any necessary operations. 

$url = $_POST['url'];

// Check if the URL does not include "www"
if (!preg_match('/www\./', $url)) {
    $url = 'www.' . $url;
}

// Further processing of the URL
// ...

Keywords

PHP URL validation user input regex domain name

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