GUIDELINES FOR PROGRAMMING LANGUAGES ASSIGNMENTS

A) Indent your code to show the program structure. The style I favour is
   exemplified by the code appended below but there are many possible ways
   of doing indentation and placing the braces - the important thing is that
   you should pick one style and be consistent in using it.

B) Use meaningful variable names. Single letter variable names such as 'i'
   are fine for obvious things like loop counters but most variables should
   be at least 3 characters long and should have a name related to their use
   in the program.

C) Avoid use of file-scope variables and (especially) global variables
   except where absolutely necessary. The instructions to the assignment
   will usually make it clear if file-scope variables are to be used.
   In general, variables should be defined at the smallest scope possible.

D) Comment your code. Each function should have a "header comment" that
   explains the purpose of the function, its inputs, outputs, and return value.
   Extra comments should appear inside the function to explain any code
   which is less than obvious.

E) Follow the instructions for the assignment precisely !
   Eg. if the assignment says to have a function that takes three float
   parameters - don't use an array with three elements instead.
   Don't solve a more general problem than was posed - this makes difficulties
   for the marker in trying to compare with the other students' work.

/***************************************************************************
NAME:   calc_average(int values[], int num_values)
INPUT:  values              : array of non-negative values
        num_values          : number of values
OUTPUT: ---
RETURN: float               : average of the values
DESCRIPTION:  Calculates the average of the array of values.
Exits the program with an error message if any of the values is negative.
---------------------------------------------------------------------------*/
float    calc_average(int values[], int num_values)
{
    int    sum = 0;

    for (int i = 0; i < num_values; i++)
    {
        if (values[i] >= 0)
        {
            sum += values[i];
        }
        else
        {
            // Negative values are a fatal error
            cerr << "Error: value #" << i 
                 << " is negative (" << values[i] << ")\n";
            exit(1);
        }
    }
    
    float avg = static_cast<float>(sum) / num_values;
    return avg;
}