/*Write a program in C to print grade of students*/
//Switch case => grading, if/else => validations, round() => round off

#include<stdio.h>
#include<math.h>
int main ()
{
	int result;
	float m1, m2, m3, resultFloat;
	printf ("\nEnter the marks of three subjects: ");
	scanf ("%f%f%f", &m1, &m2, &m3); 
	if ((m1>100 || m2>100 ||m3>100) || (m1<0 || m2<0 || m3<0)) //validates inputs
		printf ("\nEneter valid marks of each subject (out of 100)");
	else {
		resultFloat = (m1+m2+m3)/3;
		printf("\nThe average of marks entered is %f",resultFloat);
		result = round((m1+m2+m3)/3);
		printf("\nRounding off avg. marks...\nNew avg. marks: %d",result);
		
		switch (result)
		{
			case 91 ... 100:
				printf ("\nGrade 'O'");
				break;
			case 81 ... 90:
				printf ("\nGrade 'E'");
				break;
			case 71 ... 80:
				printf ("\nGrade 'A'");
				break;
			case 61 ... 70:
				printf ("\nGrade 'B'");
				break;
			case 51 ... 60:
				printf ("\nGrade 'C'");
				break;
			case 40 ... 50:
				printf ("\nGrade 'D'");
				break;
			case 0 ... 39:
				printf ("\nGrade 'F' (Fail)");
				break;
			default:
				printf ("\nAn error occured while caculation");
		}
	}		
	return 0;
}