/* ****************************************************************
   ex01/prog03.c
   Last update: Sep 10 2026
**************************************************************** */
#include <stdio.h>

char ScoreToGrade(int);
int  GradeToPoint(char);

int main()
{
  char gchar;
  int score, credit, point;
  int sumpoint=0, sumcredit=0;

  /* Enter score and credit */
  while (1) {
    printf("Enter score and credit (Ctrl+D to stop): ");
    if (scanf("%d%d", &score, &credit) == EOF) break;

    /* Evaluate score */
    gchar=ScoreToGrade(score);
    point=GradeToPoint(gchar);
    printf("Grade for %d is %c, Grade Point (GP) is %d. (%d credits)\n\n",
	   score, gchar, point, credit);

    /* Add score and add credit */
    sumpoint += point*credit;
    sumcredit += credit;
  }

  /* Output GPA */
  printf("\nGrade Point Average (GPA): %.3f, (Total credits: %d)\n", 
	 (double)sumpoint/sumcredit, sumcredit);

  return 0;
}


/* ****************************************
点数を評価に変換する関数
当面、0-100点以外の入力は考えない
**************************************** */
char ScoreToGrade(int score)
{
  if (score>=80) return 'A';
  else if (score>=65) return 'B';
  else if (score>=50) return 'C';
  else if (score>=35) return 'D';
  return 'F';
}


/* ****************************************
評価を評価点数に変換
**************************************** */
int GradeToPoint(char grade)
{
  if (grade=='A') return 4;
  else if (grade=='B') return 3;
  else if (grade=='C') return 2;
  else return 0; /* A-C以外は全て0 */
}