Question

我不明白为什么只有我的while语句正在工作，而且它没有转到有效整数的for语句。

import java.util.Scanner;

public class Factorial {

    public static void main(String[] args) {
        long posNumber;
        long x;
        long fact = 1;

        do {
            System.out.print("Enter a number between 2 and 15: ");
            Scanner in = new Scanner(System.in);
            posNumber = in.nextLong();
        } while (posNumber >= 2 || posNumber <= 15);


        for (x = 1; x <= posNumber; x++)
            fact = fact*x;
            System.out.println("Factorial of " +posNumber+ " is " +fact);

        }

    }

Answer 1

如果您计划在循环中获取数字，您应该尝试类似的事情：

Scanner in = new Scanner(System.in);
do {
    System.out.print("Enter a number between 2 and 15: ");
    posNumber = in.nextLong();

    for (x = 1; x <= posNumber; x++)
      fact = fact*x;
      System.out.println("Factorial of " +posNumber+ " is " +fact);
    }
} while (posNumber >= 2 || posNumber <= 15);

或者您可以更改条件（如果只运行一次）：

while (posNumber < 2 || posNumber > 15);

Answer 2

您希望程序继续询问用户该号码是否无效。这意味着如果它小于2或大于15.用以下内容替换你的while条件：

do {
    ...
} while (posNumber < 2 || posNumber > 15);

如果用户输入1，posNumber < 2将评估为true，导致循环重复并请求新号码。

如果用户输入3，则posNumber < 2和posNumber > 15将评估为false，循环将中断，然后您的for循环将执行。

Java在验证时执行

2 个答案: