java - Java 中的哨兵值

Question

我刚刚开始使用 java，对于我的介绍类，必须创建哨兵值为 0 的循环，以将输入的美元转换为英镑。有一些运行时错误，看来我是在无限循环中创建的。有人可以帮忙吗？提前致谢!

import java.util.Scanner;
/**
 * Prompts user for today's conversion of USD to GBP
 * Then prompts user for USD value, which will inform user of GBP
 * Prompting loop for other USD values, util sentinel value of (0) is encountered
 * hint: while loop shouldnt include prompt for exchange rate. When user enteres 0, program will print terminating "goodbye" message and end
 */
public class AP6_DollarToPound
{
   public static void main(String[] args)
   {
       Scanner in = new Scanner(System.in);

       double amount = 0;
       int rate = in.nextInt();
       int value = in.nextInt();

       System.out.println("Enter today's US Dollar to British Pound Sterling exchange rate: ");
       System.out.println("Enter a value in US Dollars: ");

       while (value != 0);
       {
           value = in.nextInt();
           if (value != 0)
           {
               amount = rate * value;
               System.out.println("Value in GBP is: " + value);
            }
            else
            {
                System.out.println("Goodbye!");
            }
        }
        }
    }

Answer 1

你的while循环是错误的。

while (value != 0);

这意味着当值不为零时进行迭代。在这种情况下，它始终不为零。

你应该这样做:

while (value != 0) 
{ 
    // Change value as you like
}