-------------------------------------------------------------------------------------------
本节展示如何在用户提交表单后保留输入字段中的值。
-------------------------------------------------------------------------------------------
PHP - 保留表单中的值
如需在用户点击提交按钮后在输入字段中显示值,我们在以下输入字段的 value 属性中增加了一小段 PHP 脚本:name、email 以及 website。在 comment 文本框字段中,我们把脚本放到了 <textarea> 与 </textarea> 之间。这些脚本输出 $name、$email、$website 和 $comment 变量的值。
然后,我们还需要显示选中了哪个单选按钮。对此,我们必须操作 checked 属性(而非单选按钮的 value 属性):
Name: <input type="text" name="name" value="<?php echo $name;?>"> E-mail: <input type="text" name="email" value="<?php echo $email;?>"> Website: <input type="text" name="website" value="<?php echo $website;?>"> Comment: <textarea name="comment" rows="" cols=""><?php echo $comment;?></textarea> Gender: <input type="radio" name="gender"
<?php if (isset($gender) && $gender=="female") echo "checked";?>
value="female">Female
<input type="radio" name="gender"
<?php if (isset($gender) && $gender=="male") echo "checked";?>
value="male">Male
--------------------------------------------------------------------------------------------------------------
PHP - 完整的表单实例
下面是 PHP 表单验证实例的完整代码:
实例
<!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"]);
// 检查姓名是否包含字母和空白字符
if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
$nameErr = "只允许字母和空格";
}
} if (empty($_POST["email"])) {
$emailErr = "电邮是必填的";
} else {
$email = test_input($_POST["email"]);
// 检查电子邮件地址语法是否有效
if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) {
$emailErr = "无效的 email 格式";
}
} if (empty($_POST["website"])) {
$website = "";
} else {
$website = test_input($_POST["website"]);
// 检查 URL 地址语法是否有效(正则表达式也允许 URL 中的斜杠)
if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) {
$websiteErr = "无效的 URL";
}
} if (empty($_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="" cols=""></textarea>
<br><br>
性别:
<input type="radio" name="gender" value="female">女性
<input type="radio" name="gender" value="male">男性
<span class="error">* <?php echo $genderErr;?></span>
<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>
运行结果:http://www.w3school.com.cn/tiy/s.asp?f=demo_php_form_validation_escapechar