Solution to php prompt undefined index

Usually using $_post[''], $_get[''] to obtain the parameters in the form will appear Notice: Undefined index: --------;

We often receive Undefined index errors when receiving data from POST forms, as follows:

$act=$_POST['action'];

Using the above code always prompts
Notice: Undefined index: act in D: \test\post.php on line 20
In addition, sometimes
Notice: Undefined variable: Submit... and other such prompts will appear

The above are for PHP A prompt instead of an error. PHP itself can be used directly without declaring variables in advance, but there will be a prompt for undeclared variables. Generally, as a formal website, prompts will be turned off, and even error messages will be turned off.

Solution:

Method 1: Server configuration modification
Modify the error display mode under the error configuration in php.ini:

将error_reporting = E_ALL 修改为 
error_reporting = E_ALL & ~E_NOTICE

Restart the APCHE server after modification to take effect.

Method 2: Initialize variables.

Method 3: Make a judgment

isset($_post['']),empty($_post['']) if --else

Method 4: Add @ before the notice code appears, @ indicates that there is an error in this line or a warning not to output, @$username=$ _post['username'];
Add an @ in front of the variable, such as if (@$_GET['action']=='save') { ...

Method 5: The last one This is very practical. It is a function written by someone else, and values ​​are transferred through this function.

Define a function:

The code is as follows:

function _get($str){ 
$val = !empty($_GET[$str]) ? $_GET[$str] : null; 
return $val; 
}

Then when using it, directly use _get('str') instead of $_GET['str '] That's it~

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