gpa.c

/***************************************************
Grading

A school tracks grades as A, B, C, D or E (not F).
A students GPA is a number between 0 and 4, which
you calculate by averaging the grades - an A is
given 4 points, down to an E which is given 0 points.

Write a program that reads in 4 letter grades (a 
student's first semester) and prints out his GPA.
***************************************************/
#include "si204.h"

int main() {
  // Read in four grades
  fputs("Enter four letter grades: ", stdout);
  char g1, g2, g3, g4;
  g1 = readchar(stdin);
  g2 = readchar(stdin);
  g3 = readchar(stdin);
  g4 = readchar(stdin);
  
  // Compute weights for the four grades
  int w1, w2, w3, w4;
  w1 = 'E' - g1;
  w2 = 'E' - g2;
  w3 = 'E' - g3;
  w4 = 'E' - g4;

  // Compute GPA
  double a;
  a = (double)(w1 + w2 + w3 + w4) / 4.0;

  // Print out GPA
  fputs("GPA is ", stdout);
  writenum(a, stdout);
  fputs("\n", stdout);

  return 0;
}