// using while, switch with multiple cases
// and EOF
#include <stdio.h>

int main(void)
{

	int grade;
	int aCount=0,bCount=0,cCount=0,dCount=0,eCount=0,fCount = 0;

	printf("Enter the letter grades. \n");
	printf("Enter the EOF character, ctrl-c or\n");
	printf("ctrl-z, etc to end input.\n");

	while((grade = getchar()) != EOF)
	{
		// switch nested in while loop
		switch(grade)
		{
			// grade was uppercase A or lowercase a
		case 'A': case 'a':
			++aCount;
			break;

			// grade was uppercase B or lowercase b
		case 'B': case 'b':
			++bCount;
			break;

			// grade was uppercase C or lowercase c
		case 'C': case 'c':
			++cCount;
			break;

			// grade was uppercase D or lowercase d
		case 'D': case 'd':
			++dCount;
			break;

			// grade was uppercase E or lowercase e
		case 'E': case 'e':
			++eCount;
			break;

			// grade was uppercase F or lowercase f
		case 'F': case 'f':
			++fCount;
			break;

			// ignore these input
		case '\n': case ' ':
			break;

			// catch all other characters
		default:
			{
				printf("Incorrect letter grade entered.\n");
				printf("Enter a new grade.\n");
			}
			break;
		}
	}

	// do the counting
	printf("\nTotals for each letter grade are:\n");
	printf("A:  %d\n", aCount);
	printf("B:  %d\n", bCount);
	printf("C:  %d\n", cCount);
	printf("D:  %d\n", dCount);
	printf("E:  %d\n", eCount);
	printf("F:  %d\n", fCount);

	return 0;
}