Assignment #5 solution

p0.cpp

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>
#include <cstdlib>
#include "p0.h"

using namespace std;

READWRITE::READWRITE(void)
{
	n = 0;
}

void
READWRITE::READ(void)
{
	int i, grade;
	ifstream fin;
	ofstream fout;
	
	fin.open("in.0");
	if(fin.fail()){
		n = 0;
		return;
	}
	fin >> n;
	if(n < 0 || n > 999){
		cout << "READ: invalid number of grades " << n << endl;
		n = 0;
	}
	i = 0;
	while(fin >> grade)
		if(0 <= grade && grade <= 100)
			A[i++] = grade;
	if(i != n){
		cout << "in.0: number of grades is incorrect" << endl;
		exit(2);
	}
	fin.close();
	
	fout.open("out.0");
	if(fout.fail())
		return;
	fout << n << " GRADES ARE READ." << endl;
	fout.close();
}

double
READWRITE::AVERAGE(void)
{
	int i;
	double sum;
	
	sum = 0;
	for(i = 0; i < n; i++)
		sum += A[i];
	return sum/n;
}

double
READWRITE::STD()
{
	int i;
	double sum, mu;
	
	mu = AVERAGE();
	sum = 0;
	for(i = 0; i < n; i++)
		sum += (A[i] - mu)*(A[i] - mu);
	return sqrt(sum/(n-1));
}

void
READWRITE::PRINT(void)
{
	ofstream f;
	int i;
	
	f.open("out.0", fstream::app);
	if(f.fail())
		return;
	f << n << " GRADES ARE:" << endl;
	for(i = 0; i < n; i++)
		f << A[i] << endl;
	f << endl;
	f << "average: " << fixed << setprecision(2) << AVERAGE() << endl;
	f << "std: " << fixed << setprecision(2) << STD() << endl;
	f.close();
}

void
READWRITE::REVERSE_PRINT(void)
{
	ofstream f;
	int i;
	
	f.open("out.0", fstream::app);
	if(f.fail())
		return;
	f << n << " GRADES ARE:" << endl;
	for(i = n-1; i >= 0; i--)
		f << A[i] << endl;
	f << endl;
	f << "average: " << fixed << setprecision(2) << AVERAGE() << endl;
	f << "std: " << fixed << setprecision(2) << STD() << endl;
	f.close();
}