PHP 验证示例

必填字段将检查字段是否以正确的方式填充。在大多数情况下，我们会使用 ***** 符号来表示必填字段。

什么是验证

验证意味着检查用户提交的输入。PHP中有两种类型的验证。它们如下：

客户端验证 - 验证是在客户端机器的Web浏览器上执行的。
服务器端验证 - 在数据提交后，数据会被发送到服务器并在服务器机器上执行验证检查。

一些字段的验证规则

字段	验证规则
Name	必须包含字母和空格
Email	必须包含 @ 和 .
Website	必须是一个有效的URL
Radio	必须至少能选择一次
Check Box	必须至少能选中一次
Drop Down menu	必须至少能选择一次

有效的URL

以下代码显示URL的验证。

$website = input($_POST["site"]);

if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) {
   $websiteErr = "Invalid URL"; 
}

上述语法将验证给定的URL是否有效。它应该允许一些关键字，如https，ftp，www，a-z，0-9等。

有效的电子邮件

下面的代码演示了电子邮件地址的验证。

$email = input($_POST["email"]);

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
   $emailErr = "Invalid format and please re-enter valid email"; 
}

上述语法将验证给定的电子邮件地址是否格式正确。如果不正确，将显示错误消息。

示例

下面的示例显示了带有必填字段验证的表单

<html>

   <head>
      <style>
         .error {color: #FF0000;}
      </style>
   </head>

   <body>
      <?php
         // define variables and set to empty values
          $nameErr =$ 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"]);
            }

            if (empty( $_POST["email"])) {$ emailErr = "Email is required";
            }else {
                $email = test_input($ _POST["email"]);

               // check if e-mail address is well-formed
               if (!filter_var( $email, FILTER_VALIDATE_EMAIL)) {$ emailErr = "Invalid email format"; 
               }
            }

            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 = "Gender is required";
            }else {
                $gender = test_input($ _POST["gender"]);
            }
         }

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

      <h2>Absolute classes registration</h2>

      <span class = "error">* required field.</span>

      <form method = "post" action = "<?php 
         echo htmlspecialchars( $_SERVER["PHP_SELF"]);?>"> <table> <tr> <td>Name:</td> <td><input type = "text" name = "name"> <span class = "error">* <?php echo$ nameErr;?></span>
               </td>
            </tr>

            <tr>
               <td>E-mail: </td>
               <td><input type = "text" name = "email">
                  <span class = "error">* <?php echo  $emailErr;?></span> </td> </tr> <tr> <td>Time:</td> <td> <input type = "text" name = "website"> <span class = "error"><?php echo$ websiteErr;?></span>
               </td>
            </tr>

            <tr>
               <td>Classes:</td>
               <td> <textarea name = "comment" rows = "5" cols = "40"></textarea></td>
            </tr>

            <tr>
               <td>Gender:</td>
               <td>
                  <input type = "radio" name = "gender" value = "female">Female
                  <input type = "radio" name = "gender" value = "male">Male
                  <span class = "error">* <?php echo  $genderErr;?></span> </td> </tr> <td> <input type = "submit" name = "submit" value = "Submit"> </td> </table> </form> <?php echo "<h2>Your given values are as:</h2>"; echo$ name;
         echo "<br>";

         echo  $email; echo "<br>"; echo$ website;
         echo "<br>";

         echo  $comment; echo "<br>"; echo$ gender;
      ?>

   </body>
</html>