PHP 错误：未定义索引：提交
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PHP error: Undefined index: submit
提问by Bright
Possible Duplicate:
PHP: “Notice: Undefined variable” and “Notice: Undefined index”
In this once the submit button is clicked it retrieve the data from database. But once i enter this page Undefined index: submitis shown before i click the submit button.
在此一旦单击提交按钮，它就会从数据库中检索数据。但是一旦我进入这个页面 Undefined index: submit在我点击提交按钮之前就会显示出来。
<div id="title">
<form method="get" action="<?php echo $_SERVER['PHP_SELF']?>">
<h3>Select your product and click submit</h3><br />
<select name="prod">
<option value="default">Select your product</option>
<option value="os">Operating Systems</option>
<option value="mobile">Smart Mobiles</option>
<option value="mobile">Computers</option>
<option value="shirt">Shirts</option>
</select><br /><br />
<input type="submit" value="Submit" name="submit"/>
</form>
The php code is:
php代码是：
<?php
$submitcheck=$_GET['submit'];
echo $submitcheck;
if (!isset($submitcheck)) {
echo 'Pls select and submit';
} else {
....
}
?>
?>
回答by hohner
You need to change your PHP to:
您需要将 PHP 更改为：
if (isset($_GET['submit']))
{
// Form has been submitted
}
else
{
// Form has not been submitted
}
At the moment, you're assigning a value which might not exist to $submitcheckand then checking whether it's set. You need to do it the other way round: check $_GET['submit']is set, then assign it to a variable.
目前，您正在分配一个可能不存在的值，$submitcheck然后检查它是否已设置。您需要反过来做：$_GET['submit']设置检查，然后将其分配给变量。
回答by Adrian Serafin
It's bacause you code is executed from top to bottom and on the top you are using $_GET['submit']and then this key does not exist. You could do something like that:
这是因为您的代码是从上到下执行的，并且在您使用的顶部执行$_GET['submit']，然后此密钥不存在。你可以这样做：
if(array_key_exists('submit', $_GET)){
echo $_GET['submit'];
}
or even
甚至
if (!isset($_GET['submit']))
{
echo 'Pls select and submit';
}
else
{
....
}
