以下代码将通过简单的方式来检测 name 字段是否包含字母和空格，如果 name 字段值不合法，将输出错误信息：
$name = test_input($_POST["name"]);if (!preg_match("/^[a-zA-Z ]*$/",$name)) ?{ ?$nameErr = "只允许字母及空格"; ??}
| preg_match — 进行正则表达式匹配。 语法： int preg_match ( string $pattern , string $subject [, array $matches [, int $flags ]] ) 在 subject 字符串中搜索与 pattern 给出的正则表达式相匹配的内容。如果提供了 matches ，则其会被搜索的结果所填充。$matches[0] 将包含与整个模式匹配的文本，$matches[1] 将包含与第一个捕获的括号中的子模式所匹配的文本，以此类推。 |
PHP - 验证邮件
以下代码将通过简单的方式来检测 e-mail 地址是否合法。如果 e-mail 地址不合法，将输出错误信息：
$email = test_input($_POST["email"]);if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) ?{ ?$emailErr = "非法邮件地址"; ??}
PHP - 验证 URL
以下代码将检测URL地址是否合法 (以下正则表达式运行URL中含有破折号:"-")， 如果 URL 地址不合法，将输出错误信息：
$email = test_input($_POST["email"]);if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) ?{ ?$emailErr = "非法邮件地址"; ??}
PHP - 验证 Name, E-mail, 和 URL
代码如下所示:
实例
<?php// 定义变量并设为空值$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"]); ???// check if name only contains letters and whitespace ???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($_POST["email"]); ???// check if e-mail address syntax is valid ???if (!preg_match("/([\w\-]+\@[\w\-]+\.[\w\-]+)/",$email)) ?????{ ?????$emailErr = "Invalid email format"; ??????} ???} ?if (empty($_POST["website"])) ???{$website = "";} ?else ???{ ???$website = test_input($_POST["website"]); ???// check if URL address syntax is valid (this regular expression also allows dashes in the URL) ???if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$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"]);}}?>