% cat  aveetc.C
/* 
* aveetc - Program which demonstrates the read loop for processing
* an unknown number of input lines
*
* This program reads any number of values from input until end of file
* is reached.  The count, total, and average of the values is printed.
*
* Written by: Charles Severance Tue Dec  7 10:39:23 EST 1993
*/

#include <iostream.h>

main() {

  int count;
  float value,sum,average,total;

  sum = 0.0;
  count = 0;
  total = 0.0;

/*
* Top of the read loop.  Read the values.  If end of file is encountered
* we go to line 20.  In the read statement the first asterisk is where
* to read from and the second is the FORMAT of the input.
*
* NOTE that on UNIX systems End of file can be entered
* by pressing CTRL-D when the program is reading from the terminal.
*/

  while(1) {
    cin >> value;
    if ( cin.eof() ) break;
    total = total + value;
    count = count + 1;

    cout << "Value = " <<  value << "\n";
    cout << "Running total = " << total << "\n";
    cout << "Count = " <<  count << "\n";

  } /* End while */

/* Loop exit when end of file is reached - calculate average and print out */

  cout << "We got End of FILE!!" << "\n";
  average = total/count;
  cout << "Average = " << average << "\n";

} /* End of main */
% g++  aveetc.C
% a.out 
21
Value = 21
Running total = 21
Count = 1
10
Value = 10
Running total = 31
Count = 2
7
Value = 7
Running total = 38
Count = 3
4
Value = 4
Running total = 42
Count = 4
                              <====== CTRL-D Typed
We got End of FILE!!
Average = 10.5
%