Homework 5
UCR CS10: Introduction to Computer Science
Spring Quarter 2004, Lecturer: Kris Miller

Due Wednesday, May 12 before 8:00pm by web turnin.

-------------------------------------------------------------------------------
Turnin:

Turnin this assignment to the folder, hw5, using the electronic turnin linked
to from the class webpage. For homeworks only, you may turnin .doc (Microsoft
Word) or .txt (Notepad) files. You may also turnin the homework as a .cc or
.cpp (C++ source) file. Be sure to turn it into the correct folder. At best,
you will be penalized 20%. At worst, your homework may not be graded at all.

-------------------------------------------------------------------------------
Note: Collaboration policy for this homework assignment

Collaboration on this homework is strongly ENCOURAGED. The homework is intended
for practice, not assessment -- most people who turn in decent work should get
most if not all points for this assignment. Forming study groups is strongly 
encouraged. You shouldn't simply copy answers from any source -- each other,
the book, the web, other books, previous solutions, etc. But you can certainly
discuss how to solve the problems, look over each others solutions and help
"debug" them, compare answers and redo problems if you determine your answer is
wrong, and most importantly, explain concepts related to the problems and
solutions.
-------------------------------------------------------------------------------

0. For 1 point bonus (20%), enter the names (first and last name) of the 
   CS10 students you collaborated on this homework with.

1. Self-test Exercise #5-1 (Chapter 5, Exercise #1)
2. Self-test Exercise #5-2
3. Self-test Exercise #5-3
4. Self-test Exercise #5-4 
5. Self-test Exercise #5-5
6. Self-test Exercise #5-7
7. Self-test Exercise #5-12
8. Self-test Exercise #5-13
9. Self-test Exercise #5-18

**Self-test exercises have solutions in the back of each chapter**


10. Write a program that takes 10 doubles as input from a file called 
    input.txt and outputs them to a file called output.txt. Your program should
    output the double values to a precision of 1 (1 number after the decimal
    point). You should also print to the **screen** (NOT output.txt) the avg 
    of these numbers, but with a precision of 2.



**SOLUTION**

#include <iostream>
#include <fstream>
#include <cstdlib>

using namespace std;

const int NUMBERS_IN_FILE = 10;

int main()
{
  // connect and verify input file
  ifstream fin;
  fin.open("input.txt");
  if (fin.fail())
    {
      cout << "Error opening input file\n";
      exit(1);
    }
  
  // connect and verify output file
  ofstream fout;
  fout.open("output.txt");
  if (fout.fail())
    {
      cout << "Error opening output file\n";
      exit(1);
    }

  // output formatting for output file
  fout.setf(ios::fixed);
  fout.setf(ios::showpoint);
  fout.precision(1);

  // output formatting for screen
  cout.setf(ios::fixed);
  cout.setf(ios::showpoint);
  cout.precision(2);

  int count = 0; 
  double number;
  double sum = 0;     // sum must start at 0 to work properly

  // loops NUMBERS_IN_FILE times
  while (count < NUMBERS_IN_FILE)
    {
      // get number from input file and put into output file
      fin >> number;
      fout << number << endl;
      
      // add number to sum of all numbers
      sum = sum + number;

      // keep track of how many numbers brought in
      count++;
    }

  // output avg to screen
  cout << "The average of the " << NUMBERS_IN_FILE << " numbers is: "
       << (sum / NUMBERS_IN_FILE) << endl;
 
  return 0;
}