PHP Upload principle and operation implementation

PHP Upload principle and operation implementation
There are many well-encapsulated function libraries for PHP File Upload. You can use them directly. This article only talks about the upload principle and simple upload operations, and the old bird ignores the ha _ ^ ~ There are also some security judgments, such as: the server restricts the ability to receive image files, while the client maliciously changes the extension of the virus file to an image matching file for upload. (For example, if you upload a single file, the principle of multiple files remains the same, but with little tips) copy the code in index.html <! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">