WHILE循環中的布爾語句沒有意義嗎？

Question

我的while聲明對我來說似乎沒有任何意義，即使它可行。
我希望它僅在countYears 小於 timeLimit的情況下才計算利息。...因此，如果將timeLimit設置為5，則它應該僅計算5年的利息，但以我讀取當前while語句的方式，似乎沒有這么說。 也許我只是讀錯了？

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

您所擁有的代碼無法生成正確的數據，我的成績單以每年1％的速度記錄了八年：

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

換句話說，只增加了一年的利息，而不是八年。

因此，或者您的編譯器完全是搞砸了，您的代碼不是您想像的那樣，或者您用來檢查興趣度計算的任何測試數據和/或方法都有些缺乏。

首先，正如您所countYears < timeLimit那樣，您需要將條件更改為countYears < timeLimit 。

此外，您還需要在循環之前刪除初始利息計算，因為這意味着您存入錢后將獲得全年的利息。 有了這兩個更改：

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

然后您將獲得正確的值 ：

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

如果將循環切換為<= ，則根本不會執行循環，這是正確的。

現在，您的輸出是在循環外部計算的結果。