#include <stdio.h>
#include <stdlib.h>

int grade; /* The grade the user is going to input */
char grade_value;

char grade_suffix(int grade);
int main(int argc, char *argv[])
{

  if (argc < 2) {
    printf("Please enter a grade 0-100: ");
    scanf("%d", &grade);
  } else {
    grade = atoi(argv[1]);
  }
  
  while (1) {
    if (grade > 100) {
      printf("The number had to be 100 or less");
      break;
    }
    if (grade < 0) {
      printf("The number had to be 0 or greater");
      break;
    }
    if (grade <= 60) {
      grade_value = 'F';
      break;
    }
    if (grade <= 70) {
      grade_value = 'D';
      break;
    }
    if (grade <= 80) {
      grade_value = 'C';
      break;
    }
    if (grade <= 90) {
      grade_value = 'B';
      break;
    }
    if (grade <= 100) {
      grade_value = 'A';
      break;
    }
  }
  printf("Grade value for %d is %c%c\n",grade,grade_value,grade_suffix(grade));
  return 0;
}
char grade_suffix(int grade) {
	char x[3]; /* temp space for chars */
	
	if (grade < 100) {
		snprintf(x, 3, "%d", grade);
		switch (x[1]) {
			case '0':
			case '1':
            case '2':
			case '3':
				return '-';
				break;
			case '4':
			case '5':
			case '6':
			case '7':
				return ' ';
				break;
			case '8':
			case '9':
				return '+';
				break;
		}
	} else {
		return '+';
	}
}