Average of an arbitrary amount of numbers - c

Question

I'm currently trying to create a C program for a class assignment that takes the average of an arbitrary amount of test scores. However, I've run into some problems.
My professor has provided an outline to help get started. I also can only add code where indicated, so no extra variables and such.
This is what I have so far:
#include <stdio.h>
void calculateAverage()
{
int grade, count, sum;
double average;
/* add code to input grades, calculate average, and print it */
/* --> between here */
printf("Enter the amount of test scores.\n");
scanf("%d", &count);
grade = 0;
sum = 0;
while (grade != -1 && grade <= 100 && grade >= 0)
{
printf("Enter the grade. Enter -1 when you are done entering grades.\n");
scanf("%d", &grade);
if (grade != -1 && grade <= 100 && grade >= 0)
{
sum = sum + grade;
}
else
{
average = (sum / count);
printf("average is %.2lf \n", &average);
}
}
/* --> and here */
}
int main(void)
{
while (1)
calculateAverage();
return 0;
}
So the problem I've ran into is that with what I have so far, the average will always be calculated as 0. Why exactly is this happening, and how would I fix it so it gives me the correct average?
UPDATE
So I tried casting the average to double so I can avoid a type mismatch, which did get rid of my compiler warnings but the average is still coming out to 0 for all inputed values.
#include <stdio.h>
void calculateAverage()
{
int grade, count, sum;
double average;
/* add code to input grades, calculate average, and print it */
/* --> between here */
printf("Enter the amount of test scores.\n");
scanf("%d", &count);
grade = 0;
sum = 0;
while (grade != -1 && grade <= 100 && grade >= 0)
{
printf("Enter the grade. Enter -1 when you are done entering grades.\n");
scanf("%d", &grade);
if (grade != -1 && grade <= 100 && grade >= 0)
{
sum = sum + grade;
}
else
{
average = (double)(sum / count);
printf("average is %.2f \n", &average);
}
}
/* --> and here */
}
int main(void)
{
while (1)
calculateAverage();
return 0;
}

Answer 1

#include <stdio.h>
void calculateAverage()
{
int grade, count, sum;
double average;
/* add code to input grades, calculate average, and print it */
/* --> between here */
printf("Enter the amount of test scores.\n");
scanf("%d", &count);
grade = 0;
sum = 0;
while (grade != -1 && grade <= 100 && grade >= 0)
{
printf("Enter the grade. Enter -1 when you are done entering grades.\n");
scanf("%d", &grade);
if (grade != -1 && grade <= 100 && grade >= 0)
{
sum = sum + grade;
}
else
{
average = (double)(sum / count);
printf("average is %.2lf \n", average); # <---- Please fix this!
}
}
/* --> and here */
}
int main(void)
{
while (1)
calculateAverage();
return 0;
}
There are a few problems in your code:
One is you are printing the address of average using & operator.
Another thing you can change is to use the correct format specifier when printing double.