C/C++ 中的原型设计

Question

I am trying to create the prototype and write the function called average.

I am not sure how to create it, what have gets the errors too few arguments to function..... on both lazlo and pietra

Average receives an array of student test scores.

average computes the average of the student's scores

how do i properly create the prototype?

#include <iostream>
using namespace std;

double average( int array[], int items); // function declaration (prototype)

int main()
{
    int lazlo[] = {90, 80, 85, 75, 65, -10};
    int pietra[] = { 100, 89, 83, 96, 98, 72, 78, -1};
    int num;

    num = average( lazlo );
    cout << "lazlo took " << num << "tests. Average: " << lazlo[ num ] << endl;

    num = average( pietra );
    cout << "pietra took " << num << "test. Average: " << pietra[ num ] << endl;

    // function call to average

}

Answer 1

You've declared average to take two arguments: (a pointer to the first element of) an array and the number of items in the array. The problem is that when you call average you only pass it one argument: the array (which decays into a pointer to its first element). You're missing the items argument.

Your call should look something like this:

num = average(lazlo, 6);

The messages you print afterward are also incorrect. average returns the average value, so num will be the average of the numbers in your array, not the number of items. Additionally lazlo[num] will be an error, since num will be 64 , and there is no 64th item in your lazlo array.

Answer 2

You need to have an actual function associated with the prototype in order for your code to work. You can add this below your main function:

double average( int array[], int items) {
  // write your averaging code here
}

Once you have finished coding the average function, make sure to call it such that the number of inputs and datatypes match your prototype:

num = average(lazlo, 6);
num = average(pietra, 8);