Once the form data hits the server, the PHP engine recognizes that the form contains an uploaded file or files, and creates a superglobal array called $_FILES containing various pieces of information about the file or files.
Each file is described by an element in the $_FILES array keyed on the name of the field that was used to upload the file.
Suppose your form contained a file select field called photo :
<input type="file" name="photo" value="" />
If the user uploaded a file using this field, its details would be accessible via the following PHP array element:
$_FILES[" photo" ]
This array element is itself an associative array that contains information about the file.
For example, you can find out the uploaded file's filename like this:
$filename = $_FILES[" photo" ][" name" ];
Here's a full list of the elements stored in each nested array within the $_FILES array:
| Array Element name | Description The filename of the uploaded file. |
|---|---|
| type | The MIME type of the uploaded file. For example, a JPEG image would probably have a MIME type of image/jpeg, whereas a QuickTime movie file would have a MIME type of video/quicktime. |
| size | The size of the uploaded file, in bytes. |
| tmp_name | The full path to the temporary file on the server that contains the uploaded file. |
| error | The error or status code associated with the file upload. |
The error element contains an integer value that corresponds to a built-in constant that explains the status of the uploaded file.
Possible values include:
| Constant | Value | Meaning |
|---|---|---|
| UPLOAD_ERR_OK | 0 | The file was uploaded successfully. |
| UPLOAD_ERR_INI_SIZE | 1 | The file is bigger than the allowed file size specified in the upload_max_filesize directive in the php.ini file. |
| UPLOAD_ERR_FORM_SIZE | 2 | The file is bigger than the allowed file size specified in the MAX_FILE_SIZE directive in the form. |
| UPLOAD_ERR_NO_FILE | 4 | No file was uploaded. |
| UPLOAD_ERR_NO_TMP_DIR | 6 | PHP doesn't have access to a temporary folder on the server to store the file. |
| UPLOAD_ERR_CANT_WRITE | 7 | The file couldn't be written to the server's hard disk for some reason. |
| UPLOAD_ERR_EXTENSION | 8 | The file upload was stopped by one of the currently loaded PHP extensions. |