新手教程在线编辑器

demo_form_validation_required.php:

<!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 = "姓名必填";
  } else {
    $name = test_input($_POST["name"]);
  }
  
  if (empty($_POST["email"])) {
    $emailErr = "邮箱必填";
  } 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 = "性别必填";
  } else {
    $gender = test_input($_POST["gender"]);
  }
}

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

<h2>PHP 表单验证示例</h2>
<p><span class="error">* 必填项</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>
  E-mail: <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"></textarea>
  <br><br>
  性别:
  <input type="radio" name="gender" value="female">女
  <input type="radio" name="gender" value="male">男
  <input type="radio" name="gender" value="other">其他
  <span class="error">* <?php echo $genderErr;?></span>
  <br><br>
  <input type="submit" name="submit" value="提交">  
</form>

<?php
echo "<h2>以下是你输出的内容:</h2>";
echo $name;
echo "<br>";
echo $email;
echo "<br>";
echo $website;
echo "<br>";
echo $comment;
echo "<br>";
echo $gender;
?>

</body>
</html>