A simple Grade Array Example

GradeBook.c

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

#define MAX_STUDENT 10
#define MAX_GRADE	100

int main(void)
{
	int arr[MAX_STUDENT];
	int option = -1; /* initial value */
	int i;
	int index = 0;
	int grade = 0;
	
	/* initialization of array */
	for(int i = 0; i < MAX_STUDENT; i++)
	{
		arr[i] = 0;
	}
	
	while(1)
	{
		printf("\n\nWelcome to the ARX gradebook.\n1.Enter Grade, 2.Print One Grade, 3.Print all Grades, 4. Exit.\n\n:");
		scanf("%d", &option);
		
		if(option == 1) /* insert/update grade */
		{
			printf("   Please enter an index < %d\n:", MAX_STUDENT);
			scanf("%d", &index);
			if ( (index < 0) || (index > MAX_STUDENT) )
			{
				printf("   illegal index entered!\n");
			}
			else
			{
				printf("      Please enter a grade < %d\n:", MAX_GRADE);
				scanf("%d", &grade);
				if ( (grade < 0) || (grade > MAX_GRADE) )
				{
					printf("      illegal grade entered!\n");
				}
				else
				{
					arr[index] = grade;
					printf("      [update success] Student[%d] = %d\n:", index, arr[index]);
				}
			}
		}
		
		if(option == 2) /* Print index grade */
		{
			printf("...Please enter an index < %d\n:", MAX_STUDENT);
			scanf("%d", &index);
			if ( (index < 0) || (index > MAX_STUDENT) )
			{
				printf("...illegal index entered!\n");
			}
			else
			{
				printf("...Student[%d] = %d\n", index, arr[index]);
			}
		}
		
		if(option == 3) /* Print all grades */
		{
			for(i = 0; i < MAX_STUDENT; i++)
			{
				printf("Student [%d] = %d\n", i, arr[i]);
			}
		}
		
		if(option == 4) /* Exit program */
		{
			exit(0);
		}
		
		else
		{
			printf("\nPlease enter a valid option [1,2,3,4]\n");
		}
	}
	
	return 0;
}