Question

我正在尝试做一个简单的程序，根据使用while循环和do-while循环输入的分数来验证和分配学生的成绩。我理解这很简单，代码在没有验证的情况下工作正常，但循环不循环，程序终止。这是我到目前为止所得到的

import io.*;
public class Marks {
    public static void main(String[] args) {
        double marks, inMarks;
        int assess, inAssess, calcMark, ten;
        boolean dna, dnc, fail, pass, calcDna, calcDnc, calcF, calcP;
        marks = inMarks();
        assess = inAssess();
        dna = calcDna(assess);
        dnc = calcDnc(assess);
        fail = calcF(assess, marks);
        pass = calcP(assess, marks);
        ten = calcMark(marks);

        if (dna == false) {
            if (dnc == true) {
                System.out.println("DNC-" + (int) marks);
            } else if (fail == true) {
                System.out.println("F-" + (int) marks);
            } else if (pass == true) {
                System.out.println(ten + "-" + (int) marks);
            }
        } else {
            System.out.println("DNA");
        }
    }
    private static double inMarks() {
        double marks;
        boolean validMark;
        marks = ConsoleInput.readDouble("Input student's mark");
        while ((marks < 0) && (marks > 100)) {
            System.out.println("invalid mark, please enter again");
            marks = ConsoleInput.readDouble("Input student's mark");
        }
        // Assertion 0 > marks > 100
        return marks;
    }

    private static int inAssess() {
        int assess;
        boolean validAssess;
        do {
            assess = ConsoleInput
                    .readInt("Input number of assessments student completed");
            if ((0 > assess) && (assess > 5)) {
                System.out
                        .println("invalid assessment attendence. please enter again");
            }
        } while ((0 >= assess) && (assess >= 5));
        // Assertion 0 < assess < 5
        return assess;
    }
    private static boolean calcDna(int assess) {
        boolean calcDna;
        calcDna = false;
        if ((assess == 0)) {
            calcDna = true;
        }
        return calcDna;
    }

    private static boolean calcDnc(int assess) {
        boolean calcDnc;
        calcDnc = false;
        if ((assess > 0) && (assess <= 4)) {
            calcDnc = true;
        }
        return calcDnc;
    }

    private static boolean calcF(int assess, double marks) {
        boolean calcF;
        calcF = false;
        if ((assess == 5) && (marks < 50.0)) {
            calcF = true;
        }
        return calcF;
    }

    private static boolean calcP(int assess, double marks) {
        boolean calcP;
        calcP = false;
        if ((assess == 5) && (marks > 50.0)) {
            calcP = true;
        }
        return calcP;
    }

    private static int calcMark(double marks) {
        int ten;
        ten = (int) marks / 10;
        return ten;

    }
}

Answer 1

第一个问题：

while( (marks < 0) && (marks > 100))

必须是或：

while( (marks < 0) || (marks > 100))

没有数字小于0且大于100：）

do {
    assess = ConsoleInput.readInt ("Input number of assessments student completed");
    if((0 <= assess ) || (assess >= 5))
    {
        System.out.println("invalid assessment attendence. please enter again");
    }
} while ((0 <= assess) || ( assess >= 5));

Answer 2

如果“循环不循环”，你指的是：

while( (marks < 0) && (marks > 100))

那么你的问题是marks不可能都小于零且大于100。

这里有类似的问题：

   } while ((0 >= assess) && ( assess >= 5));

assess不能小于零且大于/等于5.

Answer 3

已更改

while( (marks < 0) && (marks > 100));

while ((0 >= assess) && ( assess >= 5));

到

while( (marks < 0) || (marks > 100))

while ((0 > assess) && ( assess > 5));

使用while循环验证输入

3 个答案: