Question

我尝试使用post将我的变量q2传递给不同的页面，但它不断得到未定义的索引错误。这是我的代码：第1页：

<form action="page2.php" method="post">
Question 2: Your age ?<br> <input type = "radio" name="q2" value="a"> 15-<br>
<input type = "radio" name="q2" value ="b"> 15-25<br>
<input type = "radio" name="q2" value ="c"> 25-35<br>
<input type = "radio" name="q2" value ="d"> 35+<br>
</form>
<a href="page2.php">Submit</a>

第2页：

<?php
$q2 = $_POST['q2'];
Echo $q2;
?>

第2页输出：

Notice: Undefined index: q2 in D:\XAMPP\htdocs\page2.php

Answer 1

您的数据未被POST，因为您只是链接到page2.php。

需要改为

<form action="page2.php" method="post">
Question 2: Your age ?<br> <input type = "radio" name="q2" value="a"> 15-<br>
<input type = "radio" name="q2" value ="b"> 15-25<br>
<input type = "radio" name="q2" value ="c"> 25-35<br>
<input type = "radio" name="q2" value ="d"> 35+<br>
<input type='submit' value='Submit' />
</form>

Answer 2

我接受了这个评论。在您的表单中，您导航到page2.php，而非提交表单。

正确的方法是：

<input type = "radio" name="q2" value ="d"> 35+<br>
<!-- add the submit button inside the form -->
<input type="submit" name="submit"> 
</form>

在您的page2.php：

中

<?php
//always use isset before checking for POST variables
if(isset($_POST['submit']){
  $q2 = $_POST['q2'];
  echo $q2;
}
?>

Answer 3

You have already written in form action 

no need of this <a href="page2.php">Submit</a>

<input type="button" id="submit" name="submit" value="Submit"/>
write this line before </form> tag close instead of this line 
<a href="page2.php">Submit</a>

Answer 4

在您的代码<a href="page2.php">Submit</a>中只是一个链接。这不是表格提交。

<form action="page2.php" method="post">
Question 2: Your age ?<br> 
<input type = "radio" name="q2" value="a"> 15-<br>
<input type = "radio" name="q2" value ="b"> 15-25<br>
<input type = "radio" name="q2" value ="c"> 25-35<br>
<input type = "radio" name="q2" value ="d"> 35+<br>
</form>
<a href="page2.php">Submit</a>

在page.php中，您可以使用var_dump进行调试。类似于以下内容

<?php
$q2 = $_POST['q2'];
var_dump($q2);
echo $q2;
?>

所以你会得到null结果。

当您尝试使用表单提交时，如下所示

<form action="page2.php" method="post">
Question 2: Your age ?<br> 
<input type = "radio" name="q2" value="a"> 15-<br>
<input type = "radio" name="q2" value ="b"> 15-25<br>
<input type = "radio" name="q2" value ="c"> 25-35<br>
<input type = "radio" name="q2" value ="d"> 35+<br>
<input type='submit' value='Submit' />
</form>

您将获得类似

的内容

string(1) "a" a string(1) "b" b string(1) "c" c string(1) "d" d

将变量传递给另一个页面时的未定义索引

4 个答案: