How to use $_FILES in PHP and what to pay attention to

$_FILES: Variables submitted to the script via HTTP POST file upload, similar to the old array $HTTP_POST_FILES array (still valid, but deprecated for use). For details, please refer to POST method upload

The content of the $_FILES array is as follows:

$_FILES['myFile']['name'] The original name of the client file ​​​

$_FILES['myFile']['type'] The MIME type of the file, which requires the browser to provide support for this information, such as "image/ gif"                                                                                                                                                                                                                                            without with with the The file name is generally the system default and can be specified in upload_tmp_dir of php.ini, but setting it with the putenv() function will not work.

$_FILES['myFile']['error'] The error code related to the file upload, ['error'] was added in PHP 4.2.0 version, the following is its description: (They are in PHP3. 0 becomes a constant after 0)

UPLOAD_ERR_OK value: 0; No error occurred, the file was uploaded successfully

UPLOAD_ERR_INI_SIZE value: 1; The uploaded file exceeded the value limited by the upload_max_filesize option in php.ini​​​

UPLOAD_ERR_FORM_SIZE Value: 2; The size of the uploaded file exceeds the value specified by the MAX_FILE_SIZE option in the HTML form

UPLOAD_ERR_PARTIAL Value: 3; Only part of the file was uploaded

UPLOAD_ERR_NO_FI LE value: 4; no file was uploaded, value: 5; upload The file size is 0

1. After the file is uploaded, it is stored in the temporary directory by default. At this time, it must be deleted from the temporary directory or moved to other places. If not, then will be deleted. That is to say, regardless of whether the upload is successful or not, the files in the temporary directory will definitely be deleted after the script is executed. Therefore, you need to use PHP's copy() function to copy it to another location before deleting it. At this time, the file upload process is completed. 2. Before PHP 4.1.0, the name of this array was $HTTP_POST_FILES, which is not an automatic global variable like $_FILES. PHP 3 does not support the $HTTP_POST_FILES array.

3. When uploading files using form, be sure to add the attribute content enctype="multipart/form-data", otherwise an exception will be reported when using $_FILES[filename] to obtain file information.

<form enctype="multipart/form-data" action="URL"method="post">
       <input name="myFile" type="file">
       <input type="submit"value="上传文件">
</form>