PHP正则验证Email的方法

本文实例讲述了PHP正则验证Email的方法。分享给大家供大家参考。具体如下：

    <?php
    function 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;
    }
    ?>

PS：这里再为大家提供2款非常方便的正则表达式工具供大家参考使用：

JavaScript正则表达式在线测试工具：
http://tools.jb51.net/regex/javascript

正则表达式在线生成工具：
http://tools.jb51.net/regex/create_reg

希望本文所述对大家的php程序设计有所帮助。