Additional Notes on Set Functions

A public set function such as setCourseName should carefully scrutinize any attempt to modify the value of a data member (e.g., courseName) to ensure that the new value is appropriate for that data item. For example, an attempt to set the day of the month to 37 should be rejected, an attempt to set a person’s weight to zero or a negative value should be rejected, an attempt to set a grade on an exam to 185 (when the proper range is zero to 100) should be rejected, and so on.

A set function could return a value indicating that an attempt was made to assign invalid data to an object of the class. A client could then test the return value of the set function to determine whether the attempt to modify the object was successful and to take appropriate action if not. We will do that in later chapters after we introduce a bit more programming technology. In C++, clients of objects also can be notified of problems via the exception-handling mechanism, which we begin discussing in Chapter 7 and present indepth in Chapter 17.