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本节展示如何验证名字、电邮和 URL。
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PHP - 验证名字
以下代码展示的简单方法检查 name 字段是否包含字母和空格。如果 name 字段无效，则存储一条错误消息：
$name = test_input($_POST["name"]);
if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
$nameErr = "只允许字母和空格！";
}
注释：preg_match() 函数检索字符串的模式，如果模式存在则返回 true，否则返回 false。
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PHP - 验证 E-mail
以下代码展示的简单方法检查 e-mail 地址语法是否有效。如果无效则存储一条错误消息：
$email = test_input($_POST["email"]);
if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) {
$emailErr = "无效的 email 格式！";
}
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PHP - 验证 URL
以下代码展示的方法检查 URL 地址语法是否有效（这条正则表达式同时允许 URL 中的斜杠）。如果 URL 地址语法无效，则存储一条错误消息：
$website = test_input($_POST["website"]);
if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%
=~_|]/i",$website)) {
$websiteErr = "无效的 URL";
}
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PHP - 验证 Name、E-mail、以及 URL
现在，脚本是这样的：
实例
<?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 = "Name is required";
} else {
$name = test_input($_POST["name"]);
// 检查名字是否包含字母和空格
if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
$nameErr = "Only letters and white space allowed";
}
} if (empty($_POST["email"])) {
$emailErr = "Email is required";
} else {
$email = test_input($_POST["email"]);
// 检查电邮地址语法是否有效
if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) {
$emailErr = "Invalid email format";
}
} if (empty($_POST["website"])) {
$website = "";
} else {
$website = test_input($_POST["website"]);
// 检查 URL 地址语言是否有效（此正则表达式同样允许 URL 中的下划线）
if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%
=~_|]/i",$website)) {
$websiteErr = "Invalid URL";
}
} if (empty($_POST["comment"])) {
$comment = "";
} else {
$comment = test_input($_POST["comment"]);
} if (empty($_POST["gender"])) {
$genderErr = "Gender is required";
} else {
$gender = test_input($_POST["gender"]);
}
}
?>
源代码：
<!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：
接下来向您讲解如何防止表单在用户提交表单后清空所有输入字段。