Example code for PHP using regular validation email

This article mainly introduces the PHP regular verification email method, involving PHP regular expression validation of the relevant skills, the need for friends can refer to the following

This article describes the PHP regular verification email method. Share to everyone for your reference. Specific as follows:

<?phpfunction Validateemail ($email) {$isValid = true; $atIndex = Strrpos ($email, "@"); if (Is_bool ($atIndex) &&amp  ;! $atIndex) {$isValid = false;} else {$domain = substr ($email, $atIndex + 1);  $local = substr ($email, 0, $atIndex);  $localLen = strlen ($local);  $domainLen = strlen ($domain);  if ($localLen < 1 | | $localLen >) {//Local part length exceeded $isValid = false;  } else if ($domainLen < 1 | | $domainLen > 255) {//Domain part length exceeded $isValid = false;  } else if ($local [0] = = '. ' | | $local [$localLen-1] = = '. ')   {//Local part starts or ends with '. '  $isValid = false;  } else if (Preg_match ('/\\.\\./', $local)) {//Local part has both consecutive dots $isValid = false; } else if (!preg_match ('/^[a-za-z0-9\\-\\.  +$/', $domain)) {//character not valid on domain part $isValid = false;  } else if (Preg_match ('/\\.\\./', $domain)) {//Domain part has both consecutive dots $isValid = false; } else if (!preg_maTCH ('/^ (\\\\.| [a-za-z0-9!#%& ' _=\\/$\ ' *+?^{}|~.-]) +$/', Str_replace ("\\\\", "", $local))) {//character not valid on local part unless//local-is quoted if (!p Reg_match ('/^ ' (\\\\ "|[   ^ "]) +" $/", Str_replace (" \\\\ "," ", $local))) {$isValid = false; }} if ($isValid &&! ( CHECKDNSRR ($domain, "MX") | |  CHECKDNSRR ($domain, "A"))) {//Domain not found in DNS $isValid = false; }} return $isValid;}? >