​x
 
<!DOCTYPE HTML> 
<html>
<head>
<style>
.error {color: #FF0000;}
</style>
</head>
<body> 
​
<?php
// 定义变量并设置为空值
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $gender = $comment = $website = "";
​
if ($_SERVER["REQUEST_METHOD"] == "POST") {
   if (empty($_POST["name"])) {
     $nameErr = "姓名是必填的";
   } else {
     $name = test_input($_POST["name"]);
   }
   
   if (empty($_POST["email"])) {
     $emailErr = "电邮是必填的";
   } else {
     $email = test_input($_POST["email"]);
   }
     
   if (empty($_POST["website"])) {
     $website = "";
   } else {
     $website = test_input($_POST["website"]);
   }
​
   if (empty($_POST["comment"])) {
     $comment = "";
   } else {
     $comment = test_input($_POST["comment"]);
   }
​
   if (empty($_POST["gender"])) {
     $genderErr = "性别是必选的";
   } else {
     $gender = test_input($_POST["gender"]);
   }
}
​
function test_input($data) {
   $data = trim($data);
   $data = stripslashes($data);
   $data = htmlspecialchars($data);
   return $data;
}
?>
​
<h2>PHP 验证实例</h2>
<p><span class="error">* 必需的字段</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> 
   姓名：<input type="text" name="name">
   <span class="error">* <?php echo $nameErr;?></span>
   <br><br>
   电邮：<input type="text" name="email">
   <span class="error">* <?php echo $emailErr;?></span>
   <br><br>
   网址：<input type="text" name="website">
   <span class="error"><?php echo $websiteErr;?></span>
   <br><br>
   评论：<textarea name="comment" rows="5" cols="40">


性别： 女性 男性 *

您的输入："; echo $name; echo "
"; echo $email; echo "
"; echo $website; echo "
"; echo $comment; echo "
"; echo $gender; ?>