CMIS 102

GPA assignment.

Write a Raptor program that calculates GPA for a student.
A student can take any number of classes.
A class is from 1 to 6 credits.
A, B, C, D, and F are the possible grades.

For each class, its number of credits is multiplied by the grade's
point value to determine the class's points:
An A is worth 4 points per credit.
An B is worth 3 points per credit.
An C is worth 2 points per credit.
An D is worth 1 points per credit.
An F is worth 0 points per credit.

GPA is the sum of the points divided by the total number of credits.

Example calculation: a student took 5 classes with these grades and
credits: (points is not input by the user)

grade   credits    points
  A        3         12
  B        3          9
  B        4         12
  C        3          6
  F        4          0
        ----       ----
          17         39
GPA = 39/17 = 2.29

The program must ensure valid input values (i.e. credit values must be
between 1 and 6, grades must be A, B, C, D, or F).