If I have this classes:

1. Class, describing student with: name, faculty number, date of birth (use the first class), average.
2. Class, describing the students from a stream with:
   1. list of students (use the class from 3.)
   2. number of the stream
   3. specialty

How could I write a method for the second class that deleting a student(by fac. number or name..) from the stream. The array of students must be a dynamic.

1. I don't see anything in your problem statement that requires an array of any kind, so I don't see how anyone could answer your question.

2. Your partial listing of the problem statement refers to a "class from 3", but there is no "3" anywhere in your post, so I don't see where to go from here.

3. For best chances of meaningful help, I respectfully suggest that you show us the code that you have implemented so far, and ask specific questions about whatever it is that you don't understand or tell us what specific kind of help you would like. At least tell us how you are approaching the problem.

Regards,

Dave