/*
    CalculateGPA.java
    David G. Klick
    September 28, 2007
    CIS 111
 
    Demonstrates a loop used to calculate GPA.
*/ 

public class CalculateGPA extends CIS111App {
    public static void main(String[] args) {
        // declare and initialize variables
        int sum = 0;
        int ctr = 0;
        double gpa = 0.0;
        char grade;
      
        // display intro message
        println("\nThis program calculates GPAs\n");
      
        // priming read
        grade = getChar("Enter letter grade ('q' to quit): ");
      
        // loop to accumulate grade
        while (grade != 'q' && grade != 'Q') {
            switch (grade) {
                case 'A':
                case 'a':
                    sum = sum + 4;
                    ctr++;
                    break;
                case 'B':
                case 'b':
                    sum = sum + 3;
                    ctr++;
                    break;
                case 'C':
                case 'c':
                    sum = sum + 2;
                    ctr++;
                    break;
                case 'D':
                case 'd':
                    sum = sum + 1;
                    ctr++;
                    break;
                case 'F':
                case 'f':
                    sum = sum + 0;
                    ctr++;
                    break;
                case 'Q':
                case 'q':
                    // do nothing
                    break;
                default:
                    println("Error: Unrecognized grade entered");
            }
            grade = getChar("Enter letter grade ('q' to quit): ");
        }
      
        // only display totals if some valid grades were entered
        if (ctr > 0) {
            gpa = (double) sum / ctr;
            printf("\nFor %d grades entered, GPA is %.2f\n", ctr, gpa);
        } else {
            println("\nNo valid grades were entered");
        }
    }
}