I guess what i need to figure out is how to do this program. but i need to make the functions call by address. any help would be great.

#include <iostream>
#include <fstream>
using namespace std;

int findLarge(int x[])
{
	int i = 0;
	int largest = -99999;
	while (i < 9)
	{
		if (largest < x[i])
			largest = x[i];
		i=i + 1;
	}
	return largest;

}



double calAverage(int x[])
{
    int i = 0;
	double avg = 0.0;
	while (i<9)
	{
		avg += x[i]; 
		i++;
	}
	return avg/9;
}


int main()
{
	int a[9], i=0, total=0, average=0, lgst=0;
	ifstream file1;
	ofstream file2;
	file1.open("quiz5data.txt", ios::in);
	file2.open("quiz5output.txt");
	if(file1.is_open()==true)
		for(i=0;i<9;i++)
		file1 >> a[i];

	findLarge(a);
	calAverage(a);
	
	
	file2<< "Largest = " << findLarge(a) << endl;
	cout << "Largest = " << findLarge(a) << endl;
	
	cout << "Avg = " << calAverage(a) << endl;
	file2<< "Avg = " << calAverage(a) << endl;
	
	return 0;
}

The program looks fine to me already. What's wrong with it?

make the functions call by address

I don't know what you mean by this.

Right direction but lots of defects in OP code.
The OP title does not bear a relation to the real OP problems.
Think about:

// Never fix array size in a function!
int getLargest(const int* a, int n)
{
  int largest = 0;
  if (a && n > 0) {
      int largest = a[0];
      for (int i = 1; i < n; i++)
        if (largest < a[i])
            largest = a[i];
  }
  return largest;
}
// The same notes as above +
// integer division corrected.
double getAverage(const int* a, int n)
{
  double avg = 0.0;
  if (a && n > 0) {
      for (int i = 0; i < n; i++)
          avg += a[i];
      avg = (double)avg/n;
  }
  return avg;
}
...
// Pass array size to the functions
double average = getAverage(a,9);
int lgst    = getLargest(a,9);
// That's all, print these vars...

Yet another tip: instead of cumbersome

ifstream file1; // INPUT stream, why ios::in later?
...
file1.open("...",ios::in);
...
if (file1.is_open() == true) // why == true?

keep it simple:

ifstream file1("...");
// always test operator >> result:
for (i = 0; i < 9 && (file1 >> a[i]); i++)
    {}
if (i < 9) { // open failed or bad input
    ...    
}
This article has been dead for over six months. Start a new discussion instead.