贷款C＃控制台应用程序，利息总额不会从零开始

Posted 2023-02-17

我已经按照它应该的方式工作，除了第一行的输出显示已经汇总的利息支付的运行总额，而不是第一个利息金额。因此，如果第一个月是1.05利息，第一个月的运行总计应显示1.05。第二个月将是1.05 +新的利息金额。现在它显示例如上面，2.10作为第一个月的总数。我的逻辑搞砸了哪里？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Loan_Program

    class Loan
    
        //declare variables
        private double LoanAmount, InterestRate;
        private int LoanLength;

        //Constructor of Loan class that takes amount, rate and years
        public Loan(double amount, double rate, int years)
        
            this.LoanAmount = amount;
            this.InterestRate = (rate / 100.0) / 12.0;
            this.LoanLength = years;
        
        //returns the monnthly payment
        public double GetMonthlyPayment()
        
            int months = LoanLength * 12;
            return (LoanAmount * InterestRate * Math.Pow(1 + InterestRate, months)) / (Math.Pow(1 + InterestRate, months) - 1);
        
        //Calculates totl interterest paid and doubles it, then returns the amount
        public double TotalInterestPaid(double number1,double number2)
        
            double TotalInterest = number1+number2;

            return  TotalInterest;
        


        //prints the amortization of Loan
        public void LoanTable()
        
            double monthlyPayment = GetMonthlyPayment();//calculates monthly payment
            double principalPaid = 0;
            double newBalance = 0;
            double interestPaid = 0;
            double principal = LoanAmount;
            double totalinterest = 0;
            //nonth, payment amount, principal paid, interest paid, total interest paid, balance
            Console.WriteLine("0,101,102,103,104,105,10", "Payment Number", "Payment Amt", "Interest Paid", "Principal paid","Balance Due","Total Interest Paid");
            for (int month = 1; month <= LoanLength * 12; month++)
            
                // Compute amount paid and new balance for each payment period
                interestPaid = principal * InterestRate;
                principalPaid = monthlyPayment - interestPaid;
                newBalance = principal - principalPaid;
                totalinterest += interestPaid;
                // Output the data item              
                Console.WriteLine("0,-101,10:N22,10:N23,10:N24,10:N25,10:N2",
 month, monthlyPayment, interestPaid, principalPaid, newBalance, TotalInterestPaid(totalinterest,interestPaid));
                // Update the balance
                principal = newBalance;
            
        

    

主要计划

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Loan_Program

    class LoanTest
    
        static void Main(string[] args)
        
            //declare variables
            double amount;
            double rate;
            int years;
            //prompt loan amount
            Console.WriteLine("Enter loan amount");
            amount = Convert.ToDouble(Console.ReadLine());//accepts console input and assigne to variable
            //prompt for rate
            Console.WriteLine("Enter annual interest rate");
            rate = Convert.ToDouble(Console.ReadLine());//accepts console input and assigne to variable
            //prompt for monhts
            Console.WriteLine("Enter number of years");
            years = Convert.ToInt32(Console.ReadLine());//accepts console input and assigne to variable

            Loan loan = new Loan(amount, rate, years);//create  new instance, send values to the class

            loan.LoanTable();

            Console.ReadKey();
        
    

答案

在计算新的totalinterest之前增加interestPaid。

    //prints the amortization of Loan
    public void LoanTable()
    
        double monthlyPayment = GetMonthlyPayment();//calculates monthly payment
        double principalPaid = 0;
        double newBalance = 0;
        double interestPaid = 0;
        double principal = LoanAmount;
        double totalinterest = 0;
        //nonth, payment amount, principal paid, interest paid, total interest paid, balance
        Console.WriteLine("0,101,102,103,104,105,10", "Payment Number", "Payment Amt", "Interest Paid", "Principal paid", "Balance Due", "Total Interest Paid");
        for (int month = 1; month <= LoanLength * 12; month++)
        
            // Compute amount paid and new balance for each payment period
            totalinterest += interestPaid;
            interestPaid = principal * InterestRate;
            principalPaid = monthlyPayment - interestPaid;
            newBalance = principal - principalPaid;
            // Output the data item              
            Console.WriteLine("0,-101,10:N22,10:N23,10:N24,10:N25,10:N2",
                month, monthlyPayment, interestPaid, principalPaid, newBalance, TotalInterestPaid(totalinterest, interestPaid));
            // Update the balance
            principal = newBalance;
        
    

这是正确的吗？

Enter loan amount
100
Enter annual interest rate
10
Enter number of years
1
Payment NumberPayment AmtInterest PaidPrincipal paidBalance DueTotal Interest Paid
1               8.79      0.83      7.96     92.04      0.83
2               8.79      0.77      8.02     84.02      1.60
3               8.79      0.70      8.09     75.93      2.30
4               8.79      0.63      8.16     67.77      2.93
5               8.79      0.56      8.23     59.54      3.50
6               8.79      0.50      8.30     51.24      3.99
7               8.79      0.43      8.36     42.88      4.42
8               8.79      0.36      8.43     34.45      4.78
9               8.79      0.29      8.50     25.94      5.07
10              8.79      0.22      8.58     17.37      5.28
11              8.79      0.14      8.65      8.72      5.43
12              8.79      0.07      8.72      0.00      5.50

另一答案

只是为了帮助使用decimal而不是double这里是你需要的代码：

void Main()

    //declare variables
    decimal amount;
    decimal rate;
    int years;
    //prompt loan amount
    Console.WriteLine("Enter loan amount");
    amount = Convert.ToDecimal(Console.ReadLine());//accepts console input and assigne to variable
                                                   //prompt for rate
    Console.WriteLine("Enter annual interest rate");
    rate = Convert.ToDecimal(Console.ReadLine());//accepts console input and assigne to variable
                                                 //prompt for monhts
    Console.WriteLine("Enter number of years");
    years = Convert.ToInt32(Console.ReadLine());//accepts console input and assigne to variable

    Loan loan = new Loan(amount, rate, years);//create  new instance, send values to the class

    loan.LoanTable();


class Loan

    //declare variables
    private decimal LoanAmount, InterestRate;
    private int LoanLength;

    //Constructor of Loan class that takes amount, rate and years
    public Loan(decimal amount, decimal rate, int years)
    
        this.LoanAmount = amount;
        this.InterestRate = DecPow(1m + rate / 100m, 1m / 12m) - 1m;
        this.InterestRate.Dump();
        this.LoanLength = years;
    
    //returns the monnthly payment
    public decimal GetMonthlyPayment()
    
        int months = LoanLength * 12;
        return (LoanAmount * InterestRate * DecPow(1m + InterestRate, months)) / (DecPow(1m + InterestRate, months) - 1m);
    
    //Calculates totl interterest paid and doubles it, then returns the amount
    public decimal TotalInterestPaid(decimal number1, decimal number2)
    
        decimal TotalInterest = number1 + number2;

        return TotalInterest;
    

    //prints the amortization of Loan
    public void LoanTable()
    
        decimal monthlyPayment = GetMonthlyPayment();//calculates monthly payment
        decimal principalPaid = 0m;
        decimal newBalance = 0m;
        decimal interestPaid = 0m;
        decimal principal = LoanAmount;
        decimal totalinterest = 0m;
        //nonth, payment amount, principal paid, interest paid, total interest paid, balance
        Console.WriteLine("0,101,102,103,104,105,10", "Payment Number", "Payment Amt", "Interest Paid", "Principal paid", "Balance Due", "Total Interest Paid");
        for (int month = 1; month <= LoanLength * 12; month++)
        
            // Compute amount paid and new balance for each payment period
            totalinterest += interestPaid;
            interestPaid = principal * InterestRate;
            principalPaid = monthlyPayment - interestPaid;
            newBalance = principal - principalPaid;
            // Output the data item              
            Console.WriteLine("0,-101,10:N22,10:N23,10:N24,10:N25,10:N2",
                month, monthlyPayment, interestPaid, principalPaid, newBalance, TotalInterestPaid(totalinterest, interestPaid));
            // Update the balance
            principal = newBalance;
        
    

    private decimal DecPow(decimal x, decimal y) => (decimal)System.Math.Pow((double)x, (double)y);
    private decimal DecPow(decimal x, int p)
    
        if (p == 0) return 1m;
        decimal power = 1m;
        int q = Math.Abs(p);
        for (int i = 1; i <= q; i++) power *= x;
        if (p == q)
            return power;
        return 1m / power;
    

特别注意DecPow方法。

另一答案

    static void Main(string[] args)
    
        float Amount, Year;
        float Rate;
        double total = 0;
        Console.Write("Enter Amount Per Year:");
        Amount = Convert.ToInt32(Console.ReadLine());
        Console.Write("Enter Rate :");
        Rate = Convert.ToSingle(Console.ReadLine());
        Console.Write("Enter Time :");
        Year = Convert.ToInt32(Console.ReadLine());
        for (int i = 1; i <= Year; i++)
        
            var current = Amount * (Rate / 100) * i;
            total += current;
        
        Console.WriteLine("Simple Interest is :0", total);
        Console.ReadKey();
    

The using another method i can find Total Interest