This is what I have currently, and I have no idea what to do to make it run:

void avg_sum(double a[], int n, double *avg, double *sum) {   
    int i;
    *sum = 0.0;

    for (i = 0; i < n; i  )
        *sum  = a[i];

    *avg = *sum / n; 
}

int main () {
    int array[5] = {1, 2, 3, 4, 5};
    int avg = 3;
    int sum = 2;

    avg_sum(array, 5, avg, sum);
}

I tried manipulating the arguments for running the function, but I can't figure out how to make it work. It can be simple, I just have to write a program to test the avg_sum function. That portion must remain the same.

CodePudding user response：

You want this:

int main () {
    double array[5] = {1, 2, 3, 4, 5};  // use double
    double avg = 3;
    double sum = 2;

    avg_sum(array, 5, &avg, &sum);      // call with &
}

• avg_sum operates on doubles, therefore you need to provide doubles.
• parametrers 3 and 4 must be pointers to double, therefore you need to use the address operator &.

All this is covered in the first chapters of your beginner's C txt book.

CodePudding user response：

For starters these initializations

int avg = 3;
int sum = 2;

does not make a sense.

At least it will be more meaningfully to initialize these variables by zero

int avg = 0;
int sum = 0;

The function avg_sum expects that the third and fourth arguments will be accepted by reference through pointers to them.

void avg_sum(double a[], int n, double *avg, double *sum) { 

So the function must be called like

avg_sum(array, 5, &avg, &sum);

Also the function expects that the first, third and fourth arguments declared with the type specifier double but you are passing arguments declared with the type specifier int.

The function itself should be declared and defined the following way

void avg_sum( const int a[], size_t n, double *avg,  int *sum ) 
{   
    *sum = 0;
    for ( size_t i = 0; i < n; i   )
    {
        *sum  = a[i];
    }

    *avg = n == 0 ? 0.0 : *sum / n; 
}

So within main the variables avg and sum have to be declared like

double avg = 0.0;
int sum = 0;

Also after the call of the function

avg_sum(array, 5, &avg, &sum);

it seems you should output the obtained values like for example

printf( "sum = %d, average = %.2f\n", sum, avg );