//class averge problem with sential-controlled iteration
#include<stdio.h>

// function main begihns program execution
int main(void)
{
    unsigned int counter; //number of grades average
    int grade;//grade value
    int total; //sum of grades

    float average; // number with decimal point for average

    //initialization phase
    toatl = 0 ;//initialize toatal
    counter= 0 ; //initialize loop counter

    //processing phase
    //get first grade from user
    printf("%s", Enter grade, -1 to end:");//prompt for input
    scanf("%d", &grade);//read grade from user

    //loop whille sentinel value not read yet from user
    while(grade!=1){
        total=total+grade;//add grade to total
        counter= counter + 1 ; //inreament counter

        //get next grade from user
        printf("%s","Enter grade, -1 to end");//prompt for input
        scanf("%d",&grade);//increamencounter
        }//end while

    //termination phase
    // if user entered atleast one grade
    if(counter!=0){
    //calculate average of all grades entered
        average=(float)total/ counter ;//avoid truncation

    //display average with two digits of precision
        printf("Class Average is %.2f\n", average);
        }//end if
     else{//if no grades were entered output meassage
        puts("No grades were entered");}//end else
}//end main function