Write data on the computer with Arduino I wonder if in Arduino you can modify the computer eg create a text file inside the computer using Arduino. Is there any way you can do this or something like that?

Because you can use the library #include &lt;stdio.h&gt;, which is a C++ language library to handle file on the computer.

In Arduino maybe you can create files on the computer using pointers or a library? Because using the library "Keyboard.h" you can handle the computer. The Keyboard library can interact with the computer by typing on the computer

I'm in doubt, I need your knowledge.
The keyboard library just sends key presses to the computer like a keyboard.  From the PCs point of view it's no different from you banging on the keyboard in front of it.  The Arduino can't control anything on the computer and it can't run any code on the computer.  Now if you can do what you want completely from the keyboard then arduino could send those same keypresses.  But the Arduino has no access to the PCs operating system or file system.