What does files mean in php

In PHP language, $_FILES refers to a super global variable (or super global array), which is used to store information about uploaded files. This variable stores some important information about files uploaded to the server, such as file name, file type, temporary file location, file size, etc.

In Web development, file upload is a very common function, such as users uploading avatars, uploading article pictures, etc. The $_FILES variable in PHP is used to handle this kind of file upload operation.

When the user selects the file to be uploaded on the front-end page and submits the form, the background PHP program will parse the form information, store the uploaded file information in the $_FILES variable, and then implement the file upload through code operation. The uploaded file can be stored in a directory on the server or stored in a database. The specific implementation method depends on the requirements.

The $_FILES variable mainly includes the following information:

• $_FILES['name']: file name, which is the original name of the uploaded file.
• $_FILES['type']: File type, that is, the MIME type of the uploaded file.
• $_FILES['tmp_name']: Temporary file name, that is, the temporary storage location of uploaded files on the server.
• $_FILES['error']: The error code when uploading files. If the upload is successful, the value is 0.
• $_FILES['size']: File size, that is, the size of the uploaded file, in bytes.

Specifically, when we upload a file, the information in the form will be parsed into a set of key-value pairs, which contains information about the uploaded file. For example, when we upload a file named "example.jpg", the following array will be stored in the $_FILES variable:

Array
(
    [name] => example.jpg
    [type] => image/jpeg
    [tmp_name] => /tmp/php/php6hst32
    [error] => 0
    [size] => 12345
)

The above array represents the five core elements of the uploaded file Information, we can obtain this information by accessing the corresponding elements in the $_FILES array. For example, we can get the original name of the file through $_FILES['name'], get the temporary location of the file through $_FILES['tmp_name'], etc.

It should be noted that in the PHP file upload operation, you need to ensure that the server's permissions are high enough, otherwise the file upload may fail. In addition, in order to ensure the security of uploaded files, we also need to verify the type and size of uploaded files and take some security measures to prevent possible attacks.

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