php Regex驗證Email的範例程式碼

Regex(regular expression)描述了一種字串匹配的模式（pattern），可以用來檢查一個串是否含有某種子串、將匹配的子串替換或者從某個串中取出符合某個條件的子串等。這篇文章主要介紹了PHP正則驗證Email的方法,涉及phpRegex驗證的相關技巧,需要的朋友可以參考下。具體如下：

<?phpfunction validateEmail($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)  {   // 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 two consecutive dots   $isValid = false;  }  else if (!preg_match('/^[A-Za-z0-9\\-\\.]+$/', $domain))  {   // character not valid in domain part   $isValid = false;  }  else if (preg_match('/\\.\\./', $domain))  {   // domain part has two consecutive dots   $isValid = false;  }  else if(!preg_match('/^(\\\\.|[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.-])+$/', str_replace("\\\\","",$local)))  {   // character not valid in local part unless    // local part is quoted   if (!preg_match('/^"(\\\\"|[^"])+"$/', str_replace("\\\\","",$local)))   {   $isValid = false;   }  }  if ($isValid && !(checkdnsrr($domain,"MX") || checkdnsrr($domain,"A")))  {   // domain not found in DNS   $isValid = false;  } } return $isValid;}?>