Question

我的声明对我来说似乎没有意义，即使它有效只要countYears 小于 timeLimit，我希望它只计算的兴趣....所以如果我将timeLimit设置为5，它应该只计算5年值得关注，但我阅读当前的声明的方式，它似乎并没有这么说。也许我只是读错了？

public class RandomPractice {
public static void main(String[] args)
{
    Scanner Keyboard = new Scanner(System.in);
    double intRate, begBalance, balance;
    int countYears, timeLimit;

    System.out.println("Please enter your current investment balance.");
    begBalance = Keyboard.nextDouble();

    System.out.println("Please enter your YEARLY interest rate (in decimals).");
    intRate = Keyboard.nextDouble();

    System.out.println("Please enter how long (in years) you would like to let interest accrue.");
    timeLimit = Keyboard.nextInt();

    balance = begBalance * (1 + intRate);
    countYears = 0;

    /* The way I read this while statement is as follows 
     * "While countYears is GREATER than the timeLimit...calculate the balance"
     * This makes no logical sense to me but I get the correct output? 
     * I want this code to calculate the investment interest ONLY as long as
     * countYears is LESS than timeLimit **/
    while (countYears >= timeLimit)
    {
        balance = balance + (balance * intRate);
        countYears++;
    }       

    System.out.println(balance);

  }
}

Answer 1

你所拥有的代码，不生成正确的数据，我的成绩单为8年，每年百分之一：

Please enter your current investment balance.
100
Please enter your YEARLY interest rate (in decimals).
.01
Please enter how long (in years) you would like to let interest accrue.
8
101.0

换句话说，只添加一年年，而不是八年。

所以要么你的编译器完全搞砸了，你的代码不是你想象的那样，或者你用来检查兴趣计算的测试数据和/或方法有点缺乏。

首先，正如您所预示的那样，您需要将条件更改为countYears < timeLimit。

此外，您还需要在循环之前删除初始利息计算，因为这意味着您在存入资金后立即获得全年的利息。有了这两个变化：

balance = begBalance; while (countYears < timeLimit) { balance = balance + (balance * intRate); countYears++; }

然后你得到correct value：

Please enter your current investment balance. 100 Please enter your YEARLY interest rate (in decimals). .01 Please enter how long (in years) you would like to let interest accrue. 8 108.28567056280801

Answer 2

如果您将循环切换为<=，那么您的循环根本就不会被执行。

现在你的输出是在循环之外计算的。

WHILE循环中的布尔语句没有意义吗？

2 个答案: