You need header guards on that header file. It is presumably being included twice.
Modify the header, adding these lines to the beginning and end.
#ifndef STUDENT_H #define STUDENT_H // Put the entire contents of your header here... #endif
The define doesn’t need to be
STUDENT_H… it just needs to be unique.
With these directives added, the compiler will ignore all contents of the header file if it has already been parsed.
Alternatively, while it is not standard C++, all major compilers will allow you to put a single
as the first line of the header to prevent it from being parsed multiple times.