奇怪的未定义偏移量：0错误

Question

I've the following PHP code that receives a file from an iOS app.

The information is received and for my debuggin $file is setted and has content in all its forms. The original value passed is btn-7.png and $file[0] = btn-7 .

The function is processed and all images are copied to the system as I see them in the folder.... thus I dont know why i am getting this error.

The error appear in the first line available to the function that shows $_FILES[$file]

Does anyone have an idea why this is happening?

EDIT: As I said. No need to do var_dump because I can echo $file. Also I am debbugin from iOS console can't see non-JSON results, I only rely on PHP logs to know the actual error message.

EDIT2: as requested `var_dump(); (I am working from XCode, iOS dev console, not web browser)

ob_start();

            var_dump($file);
            $e = ob_get_contents();
            ob_end_clean();
            error_log($e, 0);

the result

[06-Jun-2013 17:58:26 UTC] string(9) "btn-7.png"`

the error

[06-Jun-2013 17:24:45 UTC] PHP Notice:  Undefined offset: 0 in C:\xampp\htdocs\igym\classes\shareexercise.php on line 146

PHP

private function storeFile( $file )
        {
            $file = explode('.',$file);
            $file = $file[0];
            $msg['asd'] = $file;
            echo json_encode($msg);

            if( $_FILES[$file]["type"] !== "image/png" && $_FILES[$file]["size"] < 2048600 )
            {
                $error['error'] = 'There was a problem uploading your picture';
                echo json_encode($error);
                return 0;
            }

            if( move_uploaded_file( $_FILES[$file]['tmp_name'], IMGUPLOADDIR . '/' . $this->userID . '/' . $_FILES[$file]['name'] ) ) {
                return true;
            } else{
                //$error['error'] = 'There was a problem uploading your picture';
                //echo json_encode($error);
                return false;
            }

        }

Answer 1

$_FILES is an associative array, not a numerical array:

From: php.net

$_FILES
An associative array of items uploaded to the current script via the HTTP POST method.

You should var_dump($_FILES) and see what the structure looks like. 0 doesn't exist because the index is the field name or some other string.

Aso: A tutorial on $_FILES