#include <fstream>    // DOES fstream include iostream? NO;
#include <iostream>   // (comment this out, to see this!)
#include <cstdlib>    // (so can use exit function)
#include <string>
using namespace std;

// can we include the DATE/TIME with the appended total?

// consider: what is DIFFERENT between this opening
//           comment block, and that for io2.cpp?
//           What is the SAME?

// Contract: void -> int
// Purpose: interactively find out how many rats there 
//          are, get their weights, and determine the total
//          of all of their weights. Append this total weight
//          in a message to the end of file 
//          "allRatWeights.txt" in the directory from 
//          where this program is run (or create this file
//          with this as its first line, if it didn't 
//          already exist).
//
// Examples: if, when prompted, the user enters 4,
//           then the user should be prompted to enter
//           4 rat weights; if the 4 weights entered
//           are 13.3, 5, 27.1, and 15.5, then it
//           should append to the file "allRatWeights.txt"
//           in the current directory:
// The total weight is 60.9
//           If the user then runs this program again,
//           and this time enters 2 when prompted for
//           number of rats, and weights 500 and 1000,
//           the following will become the NEXT line in
//           "allRatWeights.txt", after the line above:
// The total weight is 1500
//
// by: Sharon M. Tuttle
// last modified: 10-28-03

int main ( )
{
    // local declarations
    double   weight, total = 0;
    int     num_rats;

    // we declare an ofstream variable, an output file 
    //    stream variable, giving it the name output_stream
    ofstream output_stream, date_out;

    ifstream date_in;

    // an output file stream needs to be OPENED using
    //    using the appropriate constant in 
    //    order to append to it --- this open function 
    //    expects two parameters, a string, representing 
    //    the name of the file where you want the output 
    //    to go, and the constant indicating appending.
    // (why open it so soon? because why get the info 
    //    from the user, if will not be able to append
    //    to output file?)
    output_stream.open("allRatWeights.txt", ios::app);
    if (output_stream.fail())
    {
        cout << "Could not open allRatWeights.txt "
             << "for appending..." << endl;
        exit(1);
    }

    // how many rats are there?
    cout << "how many rats are being entered? ";
    cin >> num_rats;

    // get each rat's weight, accumulate sum of weights
    for (int i=0; i < num_rats; i++)
    {        
	cout << "Enter the next rat weight: ";
	cin >> weight;
	total += weight;
    }
    
    // can I get the current date/time info into
    //    a file named temp_io6 in the current dir?
    system("date > temp_io6");
    
    // read from that file?
    date_in.open("temp_io6");
    if (date_in.fail())
    {
        cout << "arggh! temp_io6 wouldn't open!!"
             << endl;
        exit(1);
    }

    string myDate;
    getline(date_in, myDate); 

    // append the sum of all the rats' weights, but to
    // the output file stream instead of to
    // cout! (Notice how, once you set it up, you treat
    // it like cout...)
    output_stream <<  myDate << endl
                  <<  "The total weight is " << total 
                  << endl;

    // then, when you are done with it, you should 
    //    close your output file stream...
    output_stream.close();

    // ...and remove our temporary date file...
    system("rm temp_io6");

    return 0;
}