How can I turn plain URLs in a string into clickable hyperlinks with PHP?

Linking URLs in Strings with PHP

Linking URLs in strings can be a useful task in PHP for tasks such as generating clickable links in textual content. One common use case is converting a plain string containing URLs into HTML with clickable hyperlinks.

Syntax:

<code class="php">$string = preg_replace(
  "~[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]~",
  "<a href=\"\0\">\0</a>",
  $string
);</code>

Explanation:

• Regex Pattern: The pattern used in preg_replace matches strings starting with a protocol prefix (e.g., "http://") followed by one or more alphanumeric characters, excluding angle brackets and whitespace. It ends with alphanumeric characters or a slash.
• Replacement String: The replacement string includes HTML markup to create an anchor () tag with the matched URL as the href attribute and the original URL as the text content.

<code class="php">$input = "Look on http://www.google.com";
$output = preg_replace(
  "~[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]~",
  "<a href=\"\0\">\0</a>",
  $input
);

echo $output; // Output: "Look on <a href=\"http://www.google.com\">http://www.google.com</a>"</code>