Php acts as a server and accepts files uploaded from the client. how does the server receive the files?

Php acts as a server and accepts files uploaded by the client. how does the server receive files written locally by C ++, then I want to use PHP to write a program on the server to store the file. is it necessary to write a listener on the server, how can I link them to implement data transmission? php is used as a server to receive files uploaded by the client. how can the server receive the files uploaded by the client?
We use a client written locally in C ++, and then we want to use PHP to write a program on the server to store the file. is it necessary to write a listener on the server, how can we link them to implement data transmission on the php server?
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Add the multipart/form-data header in post mode
Php automatically identifies uploaded files

If you use the put method, you need to read the file content from the php: // input resource on the balanced object.