How is the file system organized in PHP?

Question

PHP

I just started learning PHP yesterday. I wrote a simple program for the practice of working with files:
1 - Open the file -> read the number -> display it
2 - The user presses the button -> increase the number
3 - Write the new number to the file -> Save
Calculation that different users together influence to that same number. And if two users access the file at the same time, will an error occur? Or is there some kind of protection in PHP?

Answer 1

use flock to avoid stale data
ru2.php.net/manual/ru/function.flock.php

Answer 2

You are most likely opening the file in blocking mode.
Those. until the document is released, another write will not go through.
For accuracy, attach the source to the question.