PHP 表单验证 - 验证 E-mail 和 URL

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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。