package welcome;

import java.util.Scanner;

/*

 * 一个循环程序的设计范例

 * 首先编写仅执行一次的程序(当无循环时)

 * 循环的设计步骤:

 * 1.确定程序中要重复执行的部分;

 * 2.加上循环模板 while(true){语句块;}

 * 3.重写循环控制条件,增加循环控制语句

 */

public class SubtrationQuizLoop {

    public static void main(String[] args) {

        final int NUMBER_OF_QUESTIONS = 5;

        int correctCount = 0;

        String output = "";

        long startTime = System.currentTimeMillis();

        Scanner in = new Scanner(System.in);

        int count = 0;

        while(count < NUMBER_OF_QUESTIONS){  // 重写循环控制条件,增加循环控制语句

        int number1 = (int) (Math.random() * 10);

        int number2 = (int) (Math.random() * 10);

        if (number1 < number2) {

            int temp = number1;

            number1 = number2;

            number2 = temp;

        }

        System.out.print(" What is " + number1 + " - " + number2 + " ? ");

        int answer = in.nextInt();

        if (number1 - number2 == answer) {

            System.out.println("You are correct!");

            correctCount++;

        } else {

            System.out.println(

                    "Your answer is wrong.\n" + number1 + " - " + number2 + " should be " + (number1 - number2));

        }

        count++;

        output += "\n" + number1 + "-" + number2 + "=" + answer + ((number1 - number2 == answer)? " correct" : " wrong");

    }

        long endTime = System.currentTimeMillis();

        long testTime = endTime - startTime;

        System.out.println("Correct count is " + correctCount + "\nTest time is " + testTime / 1000 + " seconds\n" + output);

 }

}