<!DOCTYPE HTML>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<html>
<head>
</head>
<body>
<?php
// define variables and set to empty values
$name = $email = $gender = $comment = $website = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$name = test_input($_POST["name"]);
$email = test_input($_POST["email"]);
$website = test_input($_POST["website"]);
$comment = test_input($_POST["comment"]);
$gender = test_input($_POST["gender"]);
}
function test_input($data) {
$data = trim($data); #去除用户输入数据中不必要的字符（多余的空格、制表符、换行）
$data = stripslashes($data); #删除用户输入数据中的反斜杠（）
$data = htmlspecialchars($data); #把特殊字符转换为 HTML 实体
return $data;
}
?>
<h2 style='display:inline'>PHP 验证实例</h2><h2>PHP 验证实例2</h2>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
姓名：<input type="text" name="name">
<br><br>
电邮：<input type="text" name="email">
<br><br>
网址：<input type="text" name="website">
<br><br>
评论：<textarea name="comment" rows="5" cols="40"></textarea>
<br><br>
性别：
<input type="radio" name="gender" value="female">女性
<input type="radio" name="gender" value="male">男性
<br><br>
<input type="submit" name="submit" value="提交">
</form>
<?php
echo "<h2>您的输入：</h2>";
echo $name;
echo "<br>";
echo $email;
echo "<br>";
echo $website;
echo "<br>";
echo $comment;
echo "<br>";
echo $gender;
?>
</body>
</html>
来源参考: http://www.w3school.com.cn/php/php_form_validation.asp 里面还有为空出现提示语，校验输入的字符符合规定的方法