我的php表单未检查在表单中输入的电子邮件是否有效

Question

在以下几件事上，我需要一些帮助：

1. 我有一个名为isValid的函数，该函数不检查在表单中输入的电子邮件是否有效？

2. 我如何在表单的文本字段中显示错误消息？

任何帮助是极大的赞赏！

下面是我的代码：

 <?php 

     //Set Variables to Empty String
     $Email     = " ";
     $Subject   = " ";
     $Name      = " ";
     $Message   = " ";

     $error    = " ";


     if(isset($_POST['submit']) )
     {

           if (empty($_POST["Email"]))
           {
              $error = "** Enter a valid email";
           }
           else
           {
              $Email = isValid($_POST["Email"]);
           }
           if (empty($_POST["Subject"]))
           {
              $error = "** Enter a subject";
           }
           else
           {
              $Subject= test_input($_POST["Subject"]);
           }
           if (empty($_POST["Name"]))
           {
              $error = "** Enter your name";
           }
           else
           {
              $Name= test_input($_POST["Name"]);
           }
           if (empty($_POST["Message"]))
           {
              $error = "** Enter your message";
           }
           else
           {
              $Message= test_input($_POST["Message"]);
           }
      }


function test_input($data)
{
   $data = trim($data);
   $data = stripslashes($data);
   $data = htmlspecialchars($data);
   return $data;
}

//isValid checks if email address is a valid one
function isValid($edata)
{   
return(preg_match("/^[-_.[:alnum:]]+@((([[:alnum:]]|[[:alnum:]][[:alnum:]-]* [[:alnum:]])\.)+(ad|ae|aero|af|ag|ai|al|am|an|ao|aq|ar|arpa|as|at|au|aw|az|ba|bb|bd|be|bf|bg|bh|bi|biz|bj|bm|bn|bo|br|bs|bt|bv|bw|by|bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|com|coop|cr|cs|cu|cv|cx|cy|cz|de|dj|dk|dm|do|dz|ec|edu|ee|eg|eh|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gh|gi|gl|gm|gn|gov|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie|il|in|info|int|io|iq|ir|is|it|jm|jo|jp|ke|kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly|ma|mc|md|mg|mh|mil|mk|ml|mm|mn|mo|mp|mq|mr|ms|mt|mu|museum|mv|mw|mx|my|mz|na|name|nc|ne|net|nf|ng|ni|nl|no|np|nr|nt|nu|nz|om|org|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|pro|ps|pt|pw|py|qa|re|ro|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|sk|sl|sm|sn|so|sr|st|su|sv|sy|sz|tc|td|tf|tg|th|tj|tk|tm|tn|to|tp|tr|tt|tv|tw|tz|ua|ug|uk|um|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye|yt|yu|za|zm|zw)$|(([0-9][0-9]?|[0-1][0-9][0-9]|[2][0-4][0-9]|[2][5][ 0-5])\.){3}([0-9][0-9]?|[0-1][0-9][0-9]|[2][0-4][0-9]|[2][5][0-5]))$/i", $edata));
}

?>

<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">

<p><label>From (Email):</label></p>
<input type="text" size="35" name="Email">
<span class="error"><?php echo $error;?></span>

<br><br>

<p><label>Subject:</label></p>
<input type="text" size="35" name="Subject">
<span class="error"><?php echo $error;?></span>

<br><br>

<p><label>Name:</label></p>
<input type="text" size="35" name="Name">
<span class="error"><?php echo $error;?></span>

<br><br>

<p><label>Message:</label></p>
<textarea type="text" cols="38" rows="6" name="Message"></textarea>
<span class="error"><?php echo $error;?></span>

<br><br>

<input type="submit" name="submit" value="submit">
<input type="reset" value="Reset">

</form>
<?php

if(empty($error))
{
// the email will be sent here
$to      = "@gmail.com";

// the email subject
$subject = 'Message from XXXX website from: ' . $Name;

// the mail message

$msg    .= "\r\nEmail:     $Email";
$msg    .= "\r\n\nSubject: $Subject";
$msg    .= "\r\n\nName:    $Name";
$msg    .= "\r\n\nMessage: $Message";


mail($to, $subject, $msg, "From: $Email\r\nReply-To: $Email\r\nReturn-Path: $Email\r\n");
}

?>

<p>Thank you <b><?=$Name;?></b> for your message. Expect a response in 1 - 3 business   days</p>    

Answer 1

验证功能

<?php
$email_a = 'joe@example.com';
$email_b = 'bogus';

if (filter_var($email_a, FILTER_VALIDATE_EMAIL)) {
    echo "This ($email_a) email address is considered valid.";
}
if (filter_var($email_b, FILTER_VALIDATE_EMAIL)) {
    echo "This ($email_b) email address is considered valid.";
}
?>

Answer 2

对于第二个问题，请像这样更改代码：

       if (empty($_POST["Email"]))
       {
          $error['Email'] = "** Enter a valid email";
       }
       .
       .
       .
       if (empty($_POST["Name"]))
       {
          $error['Name'] = "** Enter your name";
       }
.
.
.

<input type="text" size="35" name="Email">
<span class="error"><?php echo $error['Email'];?></span>

<input type="text" size="35" name="Name">
<span class="error"><?php echo $error['Name'];?></span>