preg_match_all(): Delimiter must not be alphanumeric or backslash

Question

class Check {

    private static $Data;
    private static $Format;

    public static function Email($Email) {
        self::$Data = (string) $Email;
        self::$Format = "/[a-z0-9_\.\-]+@[a-z0-9_\.\-]*[a-z0-9_\.\-]+\.[a-z]{2,4}$/";

        if (preg_match(self::$Data, self::$Format)):
            return true;
        else:
            return false;
        endif;
    }

}

Above my code where I use, the pre_match is making a mistake:

Delimiter must not be alphanumeric or backslash

I looked into it, but I couldn’t fix it. What I’m doing wrong ?

Answer 1

You are reversing the parameters, a read on manual avoids these problems.

preg_match ( string $pattern , string $subject )

The correct order would be this:

 preg_match(self::$Format,self::$Data)

This doesn’t make much sense:

if (preg_match(self::$Data, self::$Format)):
    return true;
else:
    return false;
endif;

If it’s to return true or false already return the value directly, there is no reason to if.

class Check {

    private static $Data;
    private static $Format;

    public static function Email($Email) {
        self::$Data = (string) $Email;
        self::$Format = "/[a-z0-9_\.\-]+@[a-z0-9_\.\-]*[a-z0-9_\.\-]+\.[a-z]{2,4}$/";

        return preg_match(self::$Format,self::$Data);
    }
}

It is also worth saying that the variables in this case could be local (only of the method, and not of the class).

As Rafael mentioned in the comments, if you prefer PHP you already have an alternative ready for this, which is recommended in place of your Regex (which by the way does not respect the valid standard of emails, denying things you should not).

filter_input($string, FILTER_VALIDATE_EMAIL)