java - 使用%找零时给出错误的数字

Question

我正在创建一个回馈零钱的系统。当我运行该程序时，我得到:(假设我捐了 100 美元)

You have given 100.0 dollars.
Your change is 14.670000000000002 dollars.
You will recieve:
0.6700000000000017 dollars
0.1700000000000017 quarters
0.0700000000000017 dimes
0.020000000000001697 nickels
1.6965595595053173E-15 pennies

代码

import java.util.Scanner;
public class RunGivingChange {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        double given;
        double cost = 85.33;
        double change;
        int dollars;
        int quarters;
        int dimes;
        int nickels;
        int pennies;

        Scanner input = new Scanner(System.in);

        System.out.println("Your total is " + cost + " dollars.");
        System.out.println("How much money are you giving?");
        given = input.nextDouble();
        if (given >= cost)
        {
            System.out.println("You have given " + given + " dollars.");
            change = given - cost;
            System.out.println("Your change is " + change + " dollars.");
            System.out.println("You will recieve:");

            //dollars
            change = change % 1;
            System.out.println(change + " dollars");

            //quarters
            change = change % 0.25;
            System.out.println(change + " quarters");

            //dimes
            change = change % 0.10;
            System.out.println(change + " dimes");

            //nickels
            change = change % 0.05;
            System.out.println(change + " nickels");

            //pennies
            change = change % 0.01;
            System.out.println(change + " pennies");
        }
        else if (given < cost)
        {
            System.out.println("Not enough money.");
        }
        else
        {
            System.out.println("Error.");
        }

    }

    }

Answer 1

您使用 double 浮点值来表示金钱。

不要这样做。

float 的精度约为 15 位有效数字，但其范围(和计算性能)惊人，使其可用于科学用途。

使用定点类型或 BigDecimal 表示货币值。