类与继承练习题

题〇：

【考察基本类的定义和使用】

编写一个矩形类，具有长（len）宽（wid）两个字段，默认构造函数为len和wid设置默认值，均为0，有参数构造函数根据传入参数的值为len和wid设置具体值。此外类包含以下几个方法：取长度、取宽度、计算周长、计算面积、修改矩形的长度、修改矩形的宽度等方法。

题一：

【考察静态方法、静态字段的意义和使用方式】

设计一个男女人数统计程序。定义一个Person类，包含姓名、性别、年龄三个私有字段。另包含males和females两个私有静态字段成员，用来记录男、女学生的人数；还有NumberMales和NumberFemales两个公有静态方法成员，这两个方法通过对静态字段males、females的访问返回男生总人数、女生总人数。设计其构造函数，要求完成每个Person对象的赋值和男女总人数的累加。 【答案】

using System;

namespace Exp0202 {

public enum Gender {男, 女}; public class Person {

//私有静态字段，分别统计男女人数 private static int males; private static int females; //公有字段，描述个人信息 public string Name; public Gender Sex; public int Age;

//构造函数，用来初始化对象

public Person (string name, Gender sex, int age) {

Name = name; Sex = sex; Age = age;

if (sex == Gender.男)

males++; //男生人数加1 if (sex == Gender.女)

females++; //女生人数加1

}

//返回男生人数

public static int NumberMales() {

return males; }

//返回女生人数

public static int NumberFemales() {

Return females; }

} //class Person结束

class Program {

static void Main (String[ ] args) {

//创建Person型的数组对象，用来记录6个人的信息 Person[ ] ps = new Person [6];

ps[0] = new Person (“李伟峰”, Gender.男, 20); ps[1] = new Person (“郭小雨”, Gender.女, 19);

ps[2] = new Person (“赵荣”, Gender.男, 22); ps[3] = new Person (“刘恒”, Gender.男, 21); ps[4] = new Person (“陈晶晶”, Gender.女, 21); ps[5] = new Person (“张馨”, Gender.女, 20); int NumOfMales = Person.NumberMales(); int NumOfFemales = Person.NumberFemales();

Console.WriteLine(“男生人数: {0}”,NumOfMales); Console.WriteLine(“女生人数: {0}”,NumOfFemales); Console.WriteLine(“学生名单如下: ”); foreach (Person p in ps) {

Console.Write(“{0}\\t”, p.Name); }

Console.Write(‘\\n’); Console.ReadLine(); } } }

题二：

【考察具有继承和派生的程序的编写基本形式、乘除法应用加减法的实现逻辑】

编写一个程序，包含两个类，分别用于提供两个整数的加减运算和乘除运算功能，要求具有乘除运算功能的类派生自具有加减运算功能的类，且乘法和除法的实现都不可以使用C#的

自有运算符“*”和“\\”。主函数通过对定义的类的对象的生产完成两个整数100和23的加、减、乘、除，并输出运算结果。 【答案】

//JiajianChengchu.cs

using System;

using System.Collections.Generic; using System.Linq; using System.Text;

namespace Calculate {

class Jiajian {

//protected int x, y;

/*public Jiajian(int xValue, int yValue) {

x = xValue; y = yValue; }*/

public int myadd(int x, int y) {

return x + y; }

public int mysub(int x, int y) {

return x - y; } }

class Chengchu : Jiajian {

//private int prod; //private int quot;

/*public Chengchu(int xValue, int yValue):base(xValue, yValue) { }*/

public int myMul(int x, int y) {

int prod = 0; for(int i=0; i

prod = myadd(prod, x); }

return prod;

}

public int myDiv(int x, int y) {

int balance = x; int quot = 0; while (balance >= y) {

balance -= y; quot++; }

return quot; } } }

//Program.cs using System;

using System.Collections.Generic; using System.Linq; using System.Text;

namespace Calculate {

class Program {

static void Main(string[] args) {

int a = 100; int b = 23;

Jiajian jiajianObj = new Jiajian(); int sum = jiajianObj.myadd(a, b); Console.WriteLine(\, sum); int dif = jiajianObj.mysub(a, b); Console.WriteLine(\, dif);

Chengchu chengchuObj = new Chengchu(); int prod = chengchuObj.myMul(a, b); Console.WriteLine(\, prod); int quot = chengchuObj.myDiv(a, b); Console.WriteLine(\, quot);

} } }

题三：

【考察继承与派生，protected与private的继承性，virtual方法与override功能】

编写一个学生和教师的信息打印程序。具体要求：定义一个Person类，包含编号、姓名两个字段，以及打印虚方法infoPrint。定义由Person类派生出得两个类：Teacher类和Student类。其中Teacher类额外包含职称、部门两个字段，及一个infoPrint的重写方法，用于打印teacher的全部信息；Student类额外包含班级号、成绩两个字段，和一个infoPrint的重写方法，用于打印Student的全部信息。

主函数中定义一个Student类对象，姓名：夏雨，编号：101，班级号：2，成绩：90；和一个Teacher类对象，姓名：王宁，编号：86，职称：教授，部门：计算机。并打印各自的信息。

考虑以下两种情况的编程细节差别：

（1） Person中的编号和姓名为protected类型； （2） Person中的编号和姓名为private类型；

【答案】： 情况一： //Person.cs

using System;

using System.Collections.Generic; using System.Linq; using System.Text;

namespace TeacherAndStudent {

class Person {

protected int id; protected string name;

public Person(int pid, string pname) {

id = pid; name = pname; }

public virtual void infoPrint() {

Console.WriteLine(\, id); Console.WriteLine(\, name); } }

class Teacher : Person {

private string title; private string department;

public Teacher(int tid, string tname, string ttitle, string tdep) : base(tid, tname) {

title = ttitle; department = tdep; }

public override void infoPrint() {

Console.WriteLine(\ Teacher's Id: {0}\, id); Console.WriteLine(\ Teacher's Name: {0}\, name); Console.WriteLine(\ Teacher's Title: {0}\, title);

Console.WriteLine(\ Teacher's Department: {0}\, department); } }

class Student : Person {

private int classNum ; private int score;

public Student(int tid, string tname, int cNum, int sco) : base(tid, tname) {

classNum = cNum; score = sco; }

public override void infoPrint() {

Console.WriteLine(\ Student's ID: {0}\, id); Console.WriteLine(\ Student's Name: {0}\, name);

Console.WriteLine(\ Student's Class number: {0}\, classNum); Console.WriteLine(\ Student's Score: {0}\, score); } } }

//Program.cs

using System;

using System.Collections.Generic; using System.Linq; using System.Text;

namespace TeacherAndStudent

{

class Program {

static void Main(string[] args) {

Console.WriteLine(\);

Teacher t = new Teacher(86, \, \, \); t.infoPrint();

Console.WriteLine(\);

Student s = new Student(101, \, 2, 90); s.infoPrint(); } } }

情况二： //Person.cs

using System;

using System.Collections.Generic; using System.Linq; using System.Text;

namespace TeacherAndStudent {

class Person {

private int id; private string name;

public Person(int pid, string pname) {

id = pid; name = pname; }

public virtual void infoPrint() {

Console.WriteLine(\, id); Console.WriteLine(\, name); } }

class Teacher : Person {

private string title; private string department;

public Teacher(int tid, string tname, string ttitle, string tdep)

: base(tid, tname) {

title = ttitle; department = tdep; }

public override void infoPrint() {

base.infoPrint();

Console.WriteLine(\, title);

Console.WriteLine(\, department); } }

class Student : Person {

private int classNum ; private int score;

public Student(int tid, string tname, int cNum, int sco) : base(tid, tname) {

classNum = cNum; score = sco; }

public override void infoPrint() {

base.infoPrint();

Console.WriteLine(\, classNum); Console.WriteLine(\, score); } } }

//Program.cs

using System;

using System.Collections.Generic; using System.Linq; using System.Text;

namespace TeacherAndStudent {

class Program {

static void Main(string[] args) {

Console.WriteLine(\);

Teacher t = new Teacher(86, \, \, \);

t.infoPrint();

Console.WriteLine(\);

Student s = new Student(101, \, 2, 90); s.infoPrint(); } } }

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