Usage of $ _ FILES in PHP and precautions

This article mainly introduces the usage and precautions of $ _ FILES in PHP. For more information, see $ _ FILES: variables submitted to the script through the http post file upload, similar to the old array $ HTTP_POST_FILES array (still valid, but opposed to use). For more information, see POST Upload.

The $ _ FILES array contains the following content:

$ _ FILES ['myfile'] ['name'] original name of the client file

$ _ FILES ['myfile'] ['type'] MIME type of the file, which must be supported by the browser, for example, "image/gif"

$ _ FILES ['myfile'] ['size'] size of the uploaded file, in bytes

$ _ FILES ['myfile'] ['tmp _ name'] temporary file name stored on the server after the file is uploaded. it is generally the default file name in php. the upload_tmp_dir of ini is specified, but the putenv () function does not work.

$ _ FILES ['myfile'] ['error'] error code related to the file upload. ['error'] was added in PHP 4.2.0, the following is its description: (they become constants after PHP3.0)

UPLOAD_ERR_ OK value: 0; no error occurred. the file is uploaded successfully.

UPLOAD_ERR_INI_SIZE: 1; the uploaded file exceeds the limit of 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 is uploaded.

UPLOAD_ERR_NO_FILE value: 4; no file is uploaded; value: 5; size of the uploaded file is 0

Note:

1.After the file is uploaded, it is stored in the temporary directory by default. in this case, it must be deleted from the temporary directory or moved to another place. if it does not exist, it will be deleted. That is, no matter whether the upload is successful or not, the files in the temporary directory will be deleted after the script is executed. Therefore, you must copy the file to another location using the copy () function of PHP before deleting the file. in this case, the file upload process is completed.

2.Before PHP 4.1.0, the array name is $ HTTP_POST_FILES, which is not an automatic global variable like $ _ FILES. PHP 3 does not support the $ HTTP_POST_FILES array.

3.When using form to upload FILES, you must add the attribute content enctype = "multipart/form-data". Otherwise, an exception is reported when you use $ _ FILES [filename] to obtain file information.
The code is as follows: