PHP错误：注意：未定义的索引： [英] PHP error: Notice: Undefined index:

问题描述

我正在使用PHP购物车，我似乎在各种各样的地方收到此错误注意：未定义的索引：。该错误指的是不同位置的类似编码位。例如，我有一段编码，用于计算用户决定订阅的月份的套餐价格。我有以下错误引用的变量：

I am working on a shopping cart in PHP and I seem to be getting this error "Notice: Undefined index:" in all sorts of places. The error refers to the similar bit of coding in different places. For example I have a piece of coding that calculates a package price with the months a user decides to subscribe. I have the following variables where the errors refers to:

    $month = $_POST['month'];
    $op = $_POST['op'];

$ month变量是用户在表单中输入的数字，$ op变量是不同的其值存储在用户从表单上的单选按钮中选择的可用表中的包。

The $month variable is the number the user inputs in a form, and the $op variable is different packages whose value are stored in a vriable that a user selects from radio buttons on the form.

我希望这在某种程度上是明确的。

I hope that is clear in some way.

谢谢

编辑：抱歉忘记提及当用户提交数据时它们会消失。但是当他们第一次来到页面时会显示此错误。我如何摆脱它，所以它不显示它？

Sorry forgot to mention that they do go away when the user submits the data. But when they first come to the page it displays this error. How I can get rid of it so it doesnt display it?

-

这是代码：

<?php
    $pack_1 = 3;
    $pack_2 = 6;
    $pack_3 = 9;
    $pack_4 = 12;
    $month = $_POST['month'];
    $op = $_POST['op'];
    $action = $_GET['action'];

    if ( $op == "Adopter" ) {
       $answer = $pack_1 * $month;
    }

    if ( $op == "Defender" ) {
      $answer = $pack_2 * $month;
    }

    if ( $op == "Protector" ) {
      $answer = $pack_3 * $month;
    }

    if ( $op == "Guardian" ) {
      $answer = $pack_4 * $month;
    }

    switch($action) {   
        case "adds":
            $_SESSION['cart'][$answer][$op];
            break;
    }
?>  

推荐答案

您正试图访问数组中的指标没有设定。这引发了一个通知。

You're attempting to access indicies within an array which are not set. This raises a notice.

你现在很可能会注意到它，因为你的代码已经转移到php.ini有 error_reporting的服务器设置为包含 E_NOTICE 。通过将error_reporting设置为 E_ALL&来抑制通知。 ~E_NOTICE （不推荐），或在您尝试访问索引之前验证索引是否存在：

Mostly likely you're noticing it now because your code has moved to a server where php.ini has error_reporting set to include E_NOTICE. Either suppress notices by setting error_reporting to E_ALL & ~E_NOTICE (not recommended), or verify that the index exists before you attempt to access it:

$month = array_key_exists('month', $_POST) ? $_POST['month'] : null;

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