What are some best practices for handling special placeholders like "@@xyz@@" and "@user@" in PHP regex patterns?

Special placeholders like "@@xyz@@" and "@user@" can be easily handled in PHP regex patterns by escaping the special characters "@" using a backslash "\". This ensures that the regex engine interprets "@" as a literal character rather than a special regex token. By escaping the "@" character, you can match the exact string "@@xyz@@" or "@user@" in your regex pattern without any issues.

// Example code snippet to match special placeholders like "@@xyz@@" and "@user@" in a string using PHP regex
$string = "This is a sample @@xyz@@ string with @user@ placeholders";
$pattern = "/@@xyz@@|@user@/";
preg_match_all($pattern, $string, $matches);

print_r($matches[0]);