结对编程：四则运算的实现

结对编程技术是指两位程序员坐在同一工作台前开发软件。与两位程序员各自独立工作相比，结对编程能编写出质量更高的代码。  我和一位小组成员利用结对编程一起完成了如下题目

题目描述：

l某公司程序员二柱的小孩上了小学二年级，老师让家长每天出30道（100以内）四则运算题目给小学生做。二柱立马就想到写一个小程序来做这件事。 这个事情可以用很多语言或者工具来实现：

•Excel、C/C++、Java、C#、VB、Unix Shell、Vbscript、Javascript、Perl、 Python、…

 

结对编程说明

结对对象：蔡何  博客地址：http://www.cnblogs.com/compilers/

双方贡献：1：2

结对编程照片:

源程序代码：

package com.jackchua.dijkstra;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;

/**
 * @author JackChua
 * @brief This is a program to automatically generate expressions
 * */
public class RationalComputing {

    private static int NUMS = 5; // 表达式个数的默认值
    private static int MAX_VALUE = 100; // 表达式的数值范围的默认值 代表 100 以内
    /** <Const number */

    private static List<Rational> listArr = new ArrayList<Rational>();
    /** <List To store Rational objects */
    private static final String[] OPREATORS = { "+", "-", "*", "/" };
    /** <a constant array to store operators */
    private static Scanner scanner = new Scanner(System.in);

    /** <a scanner to get data from user */

    /**
     * @brief This is the main function of this program
     * @param [in] args
     */
    public static void main(String[] args) {

        getInitMaxValueAndExpNum(); // 用户输入以确定生成几以内的表达式，以及表达式的个数

        int i = NUMS;
        listArr.clear();

        Random random = new Random(System.currentTimeMillis());
        while ((--i) >= 0) {
            int opA = random.nextInt(MAX_VALUE + 1);
            int opB = random.nextInt(MAX_VALUE + 1);
            String com = OPREATORS[random.nextInt(4)];
            boolean isWrong = true;
            // 判断是否减法有负数值存在 存在则必须重新生成
            while (isWrong) {
                if (com == "/" && (opB == 0 || (opA % opB) != 0)) { // 除数不能为0
                                                                    // 或者能被整出
                    opB = random.nextInt(MAX_VALUE + 1);
                } else if (com == "-" && opA < opB) { // 减法不能有负数
                    opA = random.nextInt(MAX_VALUE + 1);
                    opB = random.nextInt(MAX_VALUE + 1);
                } else if (com == "+" && (opA + opB) > MAX_VALUE) { // 运算的值不能大于MAX_VALUE
                    opA = random.nextInt(MAX_VALUE + 1);
                    opB = random.nextInt(MAX_VALUE + 1);
                } else if (com == "*" && (opA * opB) > MAX_VALUE) { // 运算的值不能大于
                                                                    // MAX_VALUE
                    opA = random.nextInt(MAX_VALUE + 1);
                    opB = random.nextInt(MAX_VALUE + 1);
                } else {
                    break;
                }
            }
            Rational tempRa = new Rational(opA, opB, com);
            listArr.add(tempRa);
        }
        //
        ouput(); // 输出
        input(); // 用户输入结果
        outputResult();// 输出用户是否输入正确
    }

    /**
     * @brief to determine the MAX_VLAUE of the expressions
     * @return void
     */
    public static void getInitMaxValueAndExpNum() {

        // 输入表达式计算的数值范围
        while (true) {
            System.out.println("请输入一个大于0 小于等于10000的整数，以确定表达式的数值范围:");
            if (scanner.hasNextInt()) {
                MAX_VALUE = scanner.nextInt();
                if (MAX_VALUE > 0 && MAX_VALUE <= 10000) {
                    break;
                } else {
                    System.out.println("请输入正确的范围!");
                }
            } else {
                System.out.println("请正确输入整数值!");
            }
        }

        // 输入要生成的表达式的个数
        while (true) {
            System.out.println("请输入一个大于0 小于等于100整数，代表自动生成多少个表达式:");
            if (scanner.hasNextInt()) {
                NUMS = scanner.nextInt();
                if (NUMS > 0 && NUMS <= 100) {
                    break;
                } else {
                    System.out.println("请输入正确的范围!");
                }
            } else {
                System.out.println("请正确输入整数值!");
            }
        }

    }

    /**
     * @brief this function to output the result
     * @return void
     */
    public static void outputResult() {
        int i = 1;
        for (Rational re : listArr) {
            if (re.isRight()) {
                System.out.println("第 " + i + "题结果是: 正确的!" + re.getOpA()
                        + re.getCom() + re.getOpB() + " = " + re.getValue());
            } else {
                System.out.println("第 " + i + "题结果是: 错误的!" + re.getOpA()
                        + re.getCom() + re.getOpB() + " = " + re.getValue());
            }

            i++;
        }
    }

    /**
     * @brief this function to get data from user ,than compute the result
     * @return void
     */
    public static void input() {
        int i = 0;
        System.out.println("请依次输入结果");
        for (i = 0; i < listArr.size(); i++) {
            System.out.println("还剩下" + (listArr.size() - i) + "道题");
            int result = 0;
            while (true) {
                if (scanner.hasNextInt()) {
                    result = scanner.nextInt();
                    break;
                } else {
                    scanner.next();
                    System.out.println("请输入有效的值");
                }
            }

            listArr.get(i).computing(result); // 计算本身的结果
        }
    }

    /**
     * @brief to show the expressions which are generated automatically
     * @return void
     */
    public static void ouput() {
        for (Rational ra : listArr) {
            System.out.println(ra.getOpA() + ra.getCom() + ra.getOpB());
        }

    }

}

/**
 * @brief This is a class of model of expression
 * @author JackCai
 *
 */
class Rational {

    private int opA;
    /** <This is the first operator of one expression */
    private int opB;
    /** <This is the second operator of one expression */
    private String com;
    /** <The operator of this expression */
    private int value;
    /** <The right result of this expression */
    private boolean isRight = false;
    /** <to indicate whether right or not */
    private int userValue;

    /** <to indicate the result of user input */

    /**
     * @brief This is the constructor of Rational
     * @param [in] opA The first operator
     * @param [in] opB The second operator
     * @param [in] com The operator of this expression
     * */
    public Rational(int opA, int opB, String com) {

        this.opA = opA;
        this.opB = opB;
        this.com = com;
        computeValue();
    }

    public boolean isRight() {
        return isRight;
    }

    public int getUserValue() {
        return userValue;
    }

    public int getOpA() {
        return opA;
    }

    public int getOpB() {
        return opB;
    }

    public String getCom() {
        return com;
    }

    public int getValue() {
        return value;
    }

    /**
     * @brief This function to compute the right result
     * @return void
     * */
    public void computeValue() {
        switch (com) {
        case "+":
            value = opA + opB;
            break;
        case "-":
            value = opA - opB;
            break;
        case "*":
            value = opA * opB;
            break;
        case "/":
            value = opA / opB;
            break;

        }
    }

    /***
     * @brief to judge whether right or not of user input
     * @param [in] value
     * @return void
     */
    public void computing(int value) {
        this.userValue = value;
        if (userValue == this.value) {
            this.isRight = true;
        }
    }
}

结果如下：

总结：结对编程确实有一定的优点，可以减少错误率，提高代码质量已经工作效率，期间大家互相交流和讨论，及时纠正问题，也学习了结对对象的身上优点和新的知识，受益匪浅。