Jednym z często występujących problemów wśród webmasterów jest walidacja adresu e-mail. W PHP do walidacji danych używana jest funkcja preg_match. Funkcja ta przyjmuje jako pierwszy parametr wyrażenie regularne, natomiast drugi parametr to tekst, który ma zostać sprawdzony. Do większości potrzeb wystarczą proste wyrażenia regularne, jednak jeżeli chcemy być w 100% zgodni ze standardem powinniśmy użyć wyrażenia regularnego, które jest zgodne z RFC
A dokładniej:
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Wyrażenie regularne może być szokujące pod względem zawartości. Jednak pokrywa ono wszystkie możliwe kombinacje poprawnych adresów e-mail. Aby użyć tego wyrażenia należy wprowadzić je do funkcji preg_match.
Czasem zachodzi potrzeba sprawdzenia czy e-mail naprawdę istnieje. Na stronie linuxjournal można znaleźć całkiem ciekawą funkcję do sprawdzenia poprawności oraz istnienia adresu e-mail. Oto ona:
<?php function validEmail($email) { $isValid = true; $atIndex = strrpos($email, "@"); if (is_bool($atIndex) && !$atIndex) { $isValid = false; } else { $domain = substr($email, $atIndex+1); $local = substr($email, 0, $atIndex); $localLen = strlen($local); $domainLen = strlen($domain); if ($localLen < 1 || $localLen > 64) { $isValid = false; } else if ($domainLen < 1 || $domainLen > 255) { // zbyt dluga domena $isValid = false; } else if ($local[0] == '.' || $local[$localLen-1] == '.') { $isValid = false; } else if (preg_match('/\\.\\./', $local)) { $isValid = false; } else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain)) { $isValid = false; } else if (preg_match('/\\.\\./', $domain)) { $isValid = false; } else if (!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/', str_replace("\\\\","",$local))) { if (!preg_match('/^"(\\\\"|[^"])+"$/', str_replace("\\\\","",$local))) { $isValid = false; } } if ($isValid && !(checkdnsrr($domain,"MX") || ↪checkdnsrr($domain,"A"))) { // nie znaleziono domeny w DNS $isValid = false; } } return $isValid; } //uzycie echo validEmail('kontakt@rpodwika.pl') ? "poprawny" : "niepoprawny"; ?>
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