考试系统

设计实现一个小学生数学考试系统，完成随机出题（简单的四则运算），学生答题，自动判分的功能。

package experiment;

import java.util.Scanner;


public class Arithmetic {
    public static void main(String args[]) {
        begin_test();
    }
    //随机产生数字
    public static double r_random(int min, int max) {
        double ii;
        ii = (double)(min + Math.random() * (max - min + 1));
        return ii;
    }
    //随机产生符号
    public static char make_sym()
    {
        int ii;
        ii = (int)(Math.random() * 3);
        if(ii == 0)
            return '+';
        else if(ii == 1)
            return '-';
        else if(ii == 2)
            return '*';
        else
            return '/';
    }
    //随机产生式子
    public static int make_formula(int min, int max)
    {
        int ii, ij;
        char operator;
        
        
        ii = (int)r_random(min, max);
        ij = (int)r_random(min, max);
        
        operator = make_sym();
        System.out.println("随机产生的四则运算为：" + ii + " " +  operator + " " +  ij + " = ?");
        if(operator == '+')
            return (ii + ij);
        else if(operator == '-')
            return (ii - ij);
        else if(operator == '*')
            return (ii * ij);
        else
        {
            return Math.round(ii / ij);
        }
    }
    
    //判断结果是否正确
    public static boolean test( int min, int max)
    {
        double answer, r_answer;
        System.out.println("请输入答案(注意除法时答案四舍五入取整):");
        Scanner sc = new Scanner(System.in);
        answer = make_formula(min, max);
        r_answer = sc.nextDouble();
        if(answer == r_answer) {
            System.out.println("正确！");
            return true;
        }
        else {
            System.out.println("错误！");
            return false;
        }
    }
    
    //计分
    public static double score(int num, int min, int max) {
        double sum = 0;
        double one_score = (float)(100 / num);
        for(int i = 0; i < num; i++) {
            if(test(min, max)) {
                sum += one_score;
            }
            else {
                continue;
            }
        }
        return sum;
    }
    //考试开始
    public static void begin_test() {
        int num, min, max;
        double sum;
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入需要产生的试题数：");
        num = sc.nextInt();
        System.out.println("请输入产生四则运算的范围（最小值和最大值）");
        min = sc.nextInt();
        max = sc.nextInt();
        sum = score(num, min, max);
        System.out.println("考试结束，最后得分为：" + sum);
    }
}