If I would have a file like this path. "C:\\music1.mp3" and a program will play this file.

Is it possble in C++ to detect if this file is accessed by that program and notify that in any way ?

Are you asking to programmatically detect when another program opens a particular file?

Is the other program known?

Would it be sufficient to know if the specific program opens the file, or do you need to detect if the file is opened by ANY program?

Are there any real-time constraints related to detecting file access?

Could we tell you tomorrow that the program accessed the file today?