java - 使用 Sentinels for Java 进行 While 循环

Question

我正在使用带有哨兵的 while 循环编写以下程序。
我遇到的问题包括:
(1) 探索如何获取输入的“最小分数”而不等于哨兵值。
(2)仅输入一个整数时，获取“最大分”和“最小分”。

任何帮助将不胜感激。以下是该计划的详细信息:

//Write a program that inputs a series of exam scores as integers.
//The number of scores is not limited.
//Print the number of scores entered and the largest and smallest score entered. 
//Use a sentinel to terminate the input.
    //Input: Series of exam scores as integers.
    //Output: Number of scores entered and the largest and smallest score entered.

import java.util.Scanner;

public class hwk_6_1 {
    public static void main(String [] args) {

        int exam_score;
        int number_of_scores = 0;
        int i;

        Scanner keyboard = new Scanner(System.in);
        System.out.print("Enter exam score or -1 to end: ");
        exam_score = keyboard.nextInt();

        int largest_score = 0;
        int smallest_score = 0;

        while(exam_score != -1) {
            for(i = 0; i < i + exam_score; i++) {
                System.out.print("Enter exam score or -1 to end: ");
                exam_score = keyboard.nextInt();
                number_of_scores = i;

                if(exam_score > largest_score) {
                    largest_score = exam_score;
                }
                if(exam_score < smallest_score) {
                    smallest_score = exam_score;
                }
            }
        }  
        System.out.println("The number of scores entered: " + (number_of_scores + 1) + ".");
        System.out.println("Largest score: " + largest_score + ".");
        System.out.println("Smallest score: " + smallest_score + ".");
    }
}

注意:我们不应该使用“if”来检查哨兵，而只能使用 while 循环；不要使用退出或中断。另外，我们要确保使用哨兵值和两个读取语句。该程序的代码应类似于以下算法:

read data // first data 
while not last data {
    process data
    read data 
}

Answer 1

您没有遵循伪代码，这就是您想要的:

read data // first data 
while not last data{
process data
read data 
}

这就是你所拥有的:

read data // first data 
while not last data{
read data  // <-- you are reading again and ignoring the first value
process data 
}

您需要处理数据并在循环末尾读取下一个数据以遵循目标伪代码。

此外，这种情况可以改善:

for(i = 0; i < i + exam_score; i++)

条件中不需要使用i，只需检查考试成绩是否为-1，因此可能是:

for(i = 0; exam_score != -1; i++)

分数计数也存在问题，您将 numer_of_scores 设置为 i。第一次迭代后，您将值设置为 0，并且读取了两个分数。最好在每次阅读后使用 number_of_scores++ 并且根本不要使用 i。

public static void main(String [] args)
{
    int exam_score;
    int number_of_scores = 0;

    Scanner keyboard = new Scanner(System.in);
    System.out.print("Enter exam score or -1 to end: ");
    exam_score = keyboard.nextInt();

    int largest_score = 0;
    int smallest_score = 0;

    while(exam_score != -1)
    {
        number_of_scores++;

        if(exam_score > largest_score)
        {
          largest_score = exam_score;
        }
        if(exam_score < smallest_score)
        {
          smallest_score = exam_score;
        } 
        System.out.print("Enter exam score or -1 to end: ");
        exam_score = keyboard.nextInt();
    }
    System.out.println("The number of scores entered: " + number_of_scores + ".");
    System.out.println("Largest score: " + largest_score + ".");
    System.out.println("Smallest score: " + smallest_score + ".");
}