Notice: Undefined index code example

Example 1: php undefined index

// Your array index has no value or is not referencing anything,
// The easiest way to overcome this is to simply check whether
// it has been defined
if (isset($arr[$i])) {
	// Do something
}

Example 2: php Undefined index: error

// Before using $_POST['value']    if (isset($_POST['value']))    {              // Instructions if $_POST['value'] exist    }

Example 3: Notice: Undefined index: module

function fullcalendar_legend_preprocess_block(&$variables) {
    if(isset($variables['configuration']['module']) && $variables['configuration']['module'] == 'fullcalendar_legend') {  
    $variables['attributes']['class'][] = 'fullcalendar-legend';
  }
}

Example 4: undefined index token in get_request_headers

$_POST['clientes'];

Example 5: undefined index token in get_request_headers

<input type="text" name="cliente">