9.4 Prep Lab: Add and Drop

In this lab you will allocate and free memory in a simple program where you can add or drop students from a class. We supply code for a simple student class with data members name and GPA. In main we declare a vector of pointers to the student class. You will fill in two sections of code. We do not put the class definitions/declarations in separate files so as to keep things simple for this prep lab.

1) You will define a student member function called ToString which returns a string containing basic student information. For a student named Jane with a GPA of 3.76 the string returned would be:

Jane has a GPA of 3.8 

You will create the string using an ostringstream from sstream. Note that you need to setprecision to 1 for that stream.

2) You will write the main function as specified below.

Specification for main - "Add and Drop"

Menu

Implement a looping menu which has the options shown in the example below (add, drop, print, and quit). We assume throughout this program that users will always enter reasonable valid inputs, and thus you do not need to test for inappropriate input. Of course, in real code, we would never assume that, but since you have tested inputs many times in other labs, we make this simplifying assumption.

Add student

Query a name (assume a one-word name) and GPA and create a new student object (using "new"). Then add the pointer to that object to the students vector.

Print

Print each student using the "ToString" method for the basic student info. For each student also print an index number as shown below.

Drop student

Query an index number and erase the corresponding student pointer from the students vector. Before you erase the pointer you must delete the actual object in memory (using "delete"). Otherwise your program will have a memory leak.

Remember that your vector of pointers resides together on the stack of your main function. However, the objects you create with "new," and point to from your vector, reside in arbitrary locations on the heap. Thus, it is essential that you free up the object memory in the heap with "delete."

Execution Example

Enter Option: add Student name: Barbara Barbara's GPA: 3.88 Enter Option: add Student name: George George's GPA: 3.414 Enter Option: print 0: Barbara has a GPA of 3.9 1: George has a GPA of 3.4 Enter Option: drop Index of student to drop: 1 Enter Option: print 0: Barbara has a GPA of 3.9 Enter Option: quit