confusion with For loops

[j3tt]

I'm trying to calculate an annual interest return on an investment. I need the program to display the text for each year showing incrementally how much interest is earned annually without increasing the investment.

// Programmed by Jett Bailes
// 02.03.10
// ass2.cpp : main project file.
// calculate annual return on an investment

#include "stdafx.h"
#include <iostream>
using namespace std;

int main ()
{
	// Declare variables and constants.
	int  years;
	double investment, total;
	const double RATE = 0.08;
	const int MAX_YRS = 30;


	// User enters data.
	cout << "Enter investment amount ";
	cin >> investment;
	total = investment;
	cout << "Enter the term in years ";
	cin >> years;
	
	//do not allow the number of years less than 1 or more than 30.
	while (years < 1 || years > MAX_YRS)
	{
		cout << "You must enter a value between 1 and " << MAX_YRS << endl;
		cout << "Please re-enter the term in years ";
		cin >> years;
	}

	//calculate and output results
	cout << "/n";
	for (int num = 1; num <= years; ++num)
	{
		double annual;
		annual = total * RATE;
		cout << "The annual return on year " << num << " is $" << annual << endl;
	}
return 0;
}

Everything up until the for statement is okay, I just can't seem to keep the program running, or calculate correctly.

[PanGalactic]

Don't you also want to keep track of your accumulated interest inside your for loop?

[j3tt]

The program won't stay up, why?

// Programmed by Jett Bailes
// 02.03.10
// ass2.cpp : main project file.
// calculate annual return on an investment

#include "stdafx.h"
#include <iostream>
using namespace std;

int main ()
{
	// Declare variables and constants.
	int  years;
	double investment, total;
	const double RATE = 0.08;
	const int MAX_YRS = 30;


	// User enters data.
	cout << "Enter investment amount ";
	cin >> investment;
	total = investment;
	cout << "Enter the term in years ";
	cin >> years;
	
	//do not allow the number of years less than 1 or more than 30.
	while (years < 1 || years > MAX_YRS)
	{
		cout << "You must enter a value between 1 and " << MAX_YRS << endl;
		cout << "Please re-enter the term in years ";
		cin >> years;
	}

	//calculate and output results
	cout << "/n";
	for (int num = 1; num <= years; num++)
	{	
			total += investment;
			cout << "The annual return on year " << years << " is $" << total << endl;	
	}
return 0;
}

[EvanEjk]

You need to keep
annual = total * RATE;
(line 39) from the first post.

You need to keep
total += investment;
(line 38) from your second post.

It would be a good idea though to put this:
double annual;
outside the for loop.

cout << "The annual return on year " << years << " is $" << total << endl;
needs to be:
cout << "The annual return on year " << num << " is $" << total << endl;

The slash is wrong on this line:
cout << "/n";
It should be:
cout << "\n";

This is why the calculation is wrong.
total += investment;
should be
total += annual;


At the beginning when you ask the user for their investment, you should just store it in total.
cin >> total;

[j3tt]

You might be right but I still can't get the program to stay up long enough for me to read it.

[p9h]

use system("PAUSE");

or something like

int main()
{
int i = 1;
std::cout << i << std::endl;

char f;
cin >> f;
return 0;
}

[jwC5fSEw]

Nono, not system("PAUSE");. There is a large discussion about this here: http://www.cplusplus.com/forum/beginner/1988/

My personal favorite is cin.get(), though my current IDE (Code::Blocks) stays open automatically, which is nice.