php 如何解决未定义索引错误
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How to solve undefined index error
提问by Alin
if(isset($_SESSION['evt_year'])
|| isset($_SESSION['evt_title'])
|| isset($_SESSION['evt_sdate'])
|| isset($_SESSION['evt_place'])
|| isset($_SESSION['evt_stime'])
|| isset($_SESSION['evt_etime'])
|| isset($_SESSION['evt_desc'])) {
$output.=$_GET['title']; //the error is here
}
else {
$output.="";
}
Notice the error I got:
注意我得到的错误：
Undefined index: title in C:\xampp\htdocs\ICT\abc\cal1\EventCalender\classes\EventRecordForm.php on line 13
未定义的索引：标题在 C:\xampp\htdocs\ICT\abc\cal1\EventCalender\classes\EventRecordForm.php 中的第 13 行
回答by AD7six
You are testing a lot of variables, but none of them are the variable that is read from.
您正在测试很多变量，但没有一个是从中读取的变量。
should be e.g.:
应该是例如：
if (isset($_GET['title'])) {
$output.=$_GET['title']; // there is no error here
}
回答by Patrick Moore
Just check isset()on the $_GETvariable before appending it:
只是检查isset()的$_GET变量追加之前：
if ( isset( $_GET['title'] ) ) $output.=$_GET['title'];
if ( isset( $_GET['title'] ) ) $output.=$_GET['title'];
The error occurs because $_GET['title'] has not been populated.
发生错误是因为 $_GET['title'] 尚未填充。
回答by Sliq
Before you check/use a variable, it needs to be defined or checked it it really exists. This has been introduced in PHP 5.3.0.
在检查/使用变量之前，需要定义它或检查它是否确实存在。这已在 PHP 5.3.0 中引入。
WRONG:
错误的：
$output = $_GET['title'];
CORRECT:
正确的：
if (isset($_GET['title'])) {
$output = $_GET['title'];
}
