Java 货币面额四舍五入问题

Question

因此，我被分配为我的编程课编写一个程序，该程序会提示用户并将输入的值读取为双精度值（最大输入为 [99.99] 九十九美元和九十九美分），这将代表一个货币金额。然后，我将确定代表所述金额所需的每张钞票和硬币的最少数量（10 美元钞票是所需的最大尺寸）。

我遇到了四舍五入的问题。例如，输入 99.99 将返回 3 便士，而它应该是 4 便士。我的老师明确告诉我不要超出课堂上所涵盖的材料（仅限于创建扫描仪、转换数据类型和强制转换。这意味着没有 BigDecimal）。任何帮助将不胜感激。

import java.util.Scanner;

public class MoneyConversion
{
     public static void main(String[] args)
     {
          //Set variables for input, dollars, and cents
          double inputAmount, change;
          int tens, fives, ones;
          int quarters, dimes, nickels, pennies;

          //Create scanner to setup for user input
          Scanner scan = new Scanner(System.in);

          //Scan user input and store into double
          System.out.print("Enter monetary amount: ");
          inputAmount = scan.nextDouble();

          //Extract demical or cent amount from dollar amount
          change = (inputAmount - (int) inputAmount) * 100;

          System.out.println("That's equivalent to:");

          //Extract and print denomination for ten-dollar bills
          tens = (int) inputAmount / 10;
          inputAmount = inputAmount % 10;
          System.out.println(tens + " ten dollar bills");

          //Extract and print denomination for five-dollar bills
          fives = (int) inputAmount / 5;
          inputAmount = inputAmount % 5;
          System.out.println(fives + " five dollar bills");

          //Extract and print denomination for one-dollar bills
          ones = (int) inputAmount;
          System.out.println(ones + " one dollar bills");

          //Extract and print denomination for quarters
          quarters = (int) change / 25;
          change = change % 25;
          System.out.println(quarters + " quarters");

          //Extract and print denomination for dimes
          dimes = (int) change / 10;
          change = change % 10;
          System.out.println(dimes + " dimes");

          //Extract and print denomination for nickels
          nickels = (int) change / 5;
          change = change % 5;
          System.out.println(nickels + " nickels");

          //Convert value for change to integer value and print for pennies
          pennies = (int) change;
          System.out.println(pennies + " pennies");

     }

}

Answer 1

您最好将数字转换为整数（便士的数量）并在此基础上进行计算，因为这样可以避免您现在遇到的浮点错误类型（它们是由浮点数表示为二进制）.

如果您使用this 逐步完成（您需要对输入进行硬编码才能使用它），您可以看到错误。

零钱设置为98.99999999999949，因为第20行四舍五入，所以少了一分钱