等额本金法
等额本金法最大的特点是每月的还款额不同，呈现逐月递减的状态;它是将贷款本金按还款的总月数均分，再加上上期剩余本金的利息，这样就形成月还款额，所以等额本金法第一个月的还款额最多，然后逐月减少，越还越少，计算公式为：
每月还本付息金额=(本金/还款月数)+(本金-累计已还本金)×月利率
每月本金=总本金/还款月数
每月利息=(本金-累计已还本金)×月利率
还款总利息=（还款月数+1）*贷款额*月利率/2
还款总额=(还款月数+1)*贷款额*月利率/2+贷款额
namespace ConsoleApplication28{class Program{static void Main(string[] args){double m, n, d = 0.0655, e = 0.0405, x, y, z,p,q,h;Console.Write("请选择房贷类型？A商业贷款；B公积金贷款：");string a = Console.ReadLine();if (a=="A"){Console.Write("请选择房贷期限？A；B20；年C30年 ：");string b = Console.ReadLine();if (b=="A"){Console.Write("请输入贷款金额：");m = Convert.ToInt32(Console.ReadLine());Console.Write("请输入第几个还款月：");n = Convert.ToInt32(Console.ReadLine());x = m / 120;y = x + (m-x)* (d/12);z = x + (m - (n - 1)*x) * (d / 12);p = (120 + 1) * m * (d / 12) / 2;q = p + m;Console.WriteLine("您当前月份的还款金额为:" + z);Console.WriteLine("您每期偿还的本金为:" + x);Console.WriteLine("您的最大月供为:" + y); Console.WriteLine("您应当还款的总利息为:" + p);Console.WriteLine("您应当还款的总金额为:" + q);for (int i = 0; i < 120; i++){h = x + (m - i*x) * (d / 12);Console.WriteLine("第"+(i+1)+"还款："+h+"当月偿还的利息为："+(h-x)+"剩余本金为："+(m-x*(i+1)));}}else if (b=="B"){Console.Write("请输入贷款金额：");m = Convert.ToInt32(Console.ReadLine());Console.Write("请输入第几个还款月：");n = Convert.ToInt32(Console.ReadLine());x = m / 180;y = x + (m - x) * (d / 12);z = x + (m - (n - 1) * x) * (d / 12);p = (180 + 1) * m * (d / 12) / 2;q = p +m;Console.WriteLine("您当前月份的还款金额为:" + z);Console.WriteLine("您每期偿还的本金为:" + x);Console.WriteLine("您的最大月供为:" + y);Console.WriteLine("您应当还款的总利息为:" + p);Console.WriteLine("您应当还款的总金额为:" + q);for (int i = 0; i < 180; i++){h = x + (m - i * x) * (d / 12);Console.WriteLine("第" + (i + 1) + "还款：" + h + "当月偿还的利息为：" + (h - x) + "剩余本金为：" + (m - x * (i + 1)));}}else if (b=="C"){Console.Write("请输入贷款金额：");m = Convert.ToInt32(Console.ReadLine());Console.Write("请输入第几个还款月：");n = Convert.ToInt32(Console.ReadLine());x = m / 240;y = x + (m - x) * (d / 12);z = x + (m - (n - 1) * x) * (d / 12);p = (240 + 1) * m * (d / 12) / 2;q = p + m;Console.WriteLine("您当前月份的还款金额为:" + z);Console.WriteLine("您每期偿还的本金为:" + x);Console.WriteLine("您的最大月供为:" + y);Console.WriteLine("您应当还款的总利息为:" + p);Console.WriteLine("您应当还款的总金额为:" + q);for (int i = 0; i < 240; i++)//依次列出每个月应该还多少，利息多少，剩余多少，for循环{h = x + (m - i * x) * (d / 12);Console.WriteLine("第" + (i + 1) + "还款：" + h + "当月偿还的利息为：" + (h - x) + "剩余本金为：" + (m - x * (i + 1)));}}else{Console.WriteLine("请您选择正确的代号！");}}else if (a=="B"){Console.Write("请选择房贷期限？A；B20；年C30年 ：");string b = Console.ReadLine();if (b == "A"){Console.Write("请输入贷款金额：");m = Convert.ToInt32(Console.ReadLine());Console.Write("请输入第几个还款月：");n = Convert.ToInt32(Console.ReadLine());x = m / 120;y = x + (m - x) * (e / 12);z = x + (m - (n - 1) * x) * (e / 12);p = (120 + 1) * m * (e / 12) / 2;q = p + m;Console.WriteLine("您当前月份的还款金额为:" + z);Console.WriteLine("您每期偿还的本金为:" + x);Console.WriteLine("您的最大月供为:" + y);Console.WriteLine("您应当还款的总利息为:" + p);Console.WriteLine("您应当还款的总金额为:" + q);for (int i = 0; i < 120; i++){h = x + (m - i * x) * (e / 12);Console.WriteLine("第" + (i + 1) + "还款：" + h + "当月偿还的利息为：" + (h - x) + "剩余本金为：" + (m - x * (i + 1)));}}else if (b == "B"){Console.Write("请输入贷款金额：");m = Convert.ToInt32(Console.ReadLine());Console.Write("请输入第几个还款月：");n = Convert.ToInt32(Console.ReadLine());x = m / 180;y = x + (m - x) * (e / 12);z = x + (m - (n - 1) * x) * (e / 12);p = (180 + 1) * m * (e / 12) / 2;q = p + m;Console.WriteLine("您当前月份的还款金额为:" + z);Console.WriteLine("您每期偿还的本金为:" + x);Console.WriteLine("您的最大月供为:" + y);Console.WriteLine("您应当还款的总利息为:" + p);Console.WriteLine("您应当还款的总金额为:" + q);for (int i = 0; i < 180; i++){h = x + (m - i * x) * (e / 12);Console.WriteLine("第" + (i + 1) + "还款：" + h + "当月偿还的利息为：" + (h - x) + "剩余本金为：" + (m - x * (i + 1)));}}else if (b == "C"){Console.Write("请输入贷款金额：");m = Convert.ToInt32(Console.ReadLine());Console.Write("请输入第几个还款月：");n = Convert.ToInt32(Console.ReadLine());x = m / 240;y = x + (m - x) * (e / 12);z = x + (m - (n - 1) * x) * (e / 12);p = (240 + 1) * m * (e / 12) / 2;q = p + m;Console.WriteLine("您当前月份的还款金额为:" + z);Console.WriteLine("您每期偿还的本金为:" + x);Console.WriteLine("您的最大月供为:" + y);Console.WriteLine("您应当还款的总利息为:" + p);Console.WriteLine("您应当还款的总金额为:" + q);for (int i = 0; i < 240; i++){h = x + (m - i * x) * (e / 12);Console.WriteLine("第" + (i + 1) + "还款：" + h + "当月偿还的利息为：" + (h - x) + "剩余本金为：" + (m - x * (i + 1)));}}else{Console.WriteLine("请您选择正确的代号！");}}else{Console.WriteLine("请您选择正确的代号！");}Console.Read();}}}
