// average2A2.cpp
// Averages a sequence of integers input from
// a text file specified by the user.
// The number of numbers to be averaged is the
// first number in the text file, followed by
// the numbers to be averaged.
// The filename is entered interactively
// by the user as a C-string.

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

int main()
{
   // Announce purpose of program:
   cout << "This program averages a sequence of integers "
             << "in a file specified by you." << endl << endl;

   // Obtain filename from user input, as a C-string:
   char filename[20];   // C-string with up to 19 characters
   cout << "Enter filename: ";
   cin >> filename;

   // Prepare to read from file:
   ifstream inputFile;
   inputFile.open(filename);

   // Input, error check, and echo
   // number of numbers to be averaged:
   int numberOfNumbers;
   inputFile >> numberOfNumbers;
   if ( numberOfNumbers <= 0 )
   {
      cout << "The number of numbers, " << numberOfNumbers
             << ", is invalid.  Must be > 0." << endl;
      return 1;
   }  // if
   cout << numberOfNumbers
            << " numbers will be averaged" << endl << endl;

   // Cumulative sum:
   int sum = 0;

   // Input and echo numbers to be averaged,
   // and add them to cumulative sum:
   int count = 0;
   while ( count < numberOfNumbers )
   {
      int number;
      inputFile >> number;
      cout << number << endl;
      sum += number;
      count++;
   }  // while

   // Compute the average and output the result:
   float average = (float) sum / numberOfNumbers;
   cout << endl << "The average is: "
                << average << "." << endl;

   return 0;
}  // function main