//programmer: Henry

//Program name: Interest calculator

//program start: 11/3/2023

//program ends: 11/2/2023

//Program description: this app helps you calculate interests for custom time and initial invest with custom interest rate

using System;

public class Program

{

    public static void Main()

    {

        double invest, rate;//initail variables

        int years;

        double interests;

        invest:

        Console.WriteLine("Welcome to Freedom 55 Investments");//headings

        Console.WriteLine("Principal Invested ($):");

        try{

            invest = Math.Round( Convert.ToDouble(Console.ReadLine()),2);//input + error checking

        }catch{

            Console.WriteLine("You can't type that!!");

            goto invest;//loop back

        }

        if(invest<=0){

            Console.WriteLine("Your number is too small!!");

            goto invest;//loop back if it is not bigger than 0

        }

        rate:

        Console.WriteLine("Interest Rate of Fund (%)");

        try{

            rate = Convert.ToDouble(Console.ReadLine())/100;//input + error checking

        }catch{

            Console.WriteLine("You can't type that!!");

            goto rate;//loop back

        }

        if(rate<=0 ){//set up conditions to keep the input as a valid percentage

            Console.WriteLine("You can't type that!!");

            goto rate;

        }else if( rate >= 1){

            Console.WriteLine("You can't type that!!");

            goto rate;

        }

        years:

        Console.WriteLine("Term of Investment (years):");

        try{

            years = Convert.ToInt32(Console.ReadLine());//input + error checking

        }catch{

            Console.WriteLine("You can't type that!!");

            goto years;//loop back

        }

        if(years<=0){

            Console.WriteLine("You can't type that!!");

            goto years;

        }

        Console.WriteLine("{0,20}{1,20}{2,30}","Year","Interest","Balance");//use index to get a formatted chart

        Console.WriteLine(new String('-',80));

        for(int count = 0; count < years; count++){//use the loop 

            interests = Math.Round(invest * rate, 2);//get the new interersts for each round

            invest += interests;// to keep oading the new balance by adding up new interests

            Console.WriteLine("{0,20}{1,20:C2}{2,30:C2}",count+1,interests,invest);//print out as a formatted chart

        }

​

    }

}

​

​