第三次上机报告.doc

实验三学号: 姓名: 班级:软件工程141继承与派生(4学时)一、实验目得1.学习定义与使用类得继承关系,定义派生类。2.熟悉不同继承方式下对基类成员得访问控制。3.学习利用虚基类解决二义性问题。二、实验任务 1.定义一个基类Animal,有私有整型成员变量age,构造其派生类dog,在其成员函数SetAge(int n)中直接给age赋值,瞧瞧会有什么问题,把age改为公有成员变量,还会有问题吗?编程试试瞧。 2.定义一个基类BaseClass,有整型成员变量Number,构造其派生类DerivedClass,观察构造函数与析构函数得执行情况。 3、 分析并调试以下程序运行结果,并与实际运行结果相对照。#include using namespace std;class Baseint x;public:Base(int i)x=i;coutConstuctor of Baseendl;BasecoutDestuctor of Baseendl;void showcoutx=xendl;class Derived:public BaseBase d;public:Derived(int i):Base(i),d(i)coutConstuctor of Derivedendl;DerivedcoutDestuctor of Derivedendl;int main( )Derived obj(5);obj、show;return 0; 4.定义一个车(vehicle)基类,具有MaxSpeed、Weight等成员变量,Run、Stop等成员函数,由此派生出自行车(bicycle)类、汽车(motorcar)类。自行车(bicycle)类有高度(Height)等属性,汽车(mot orcar)类有座位数(SeatNum)等属性。从bicycle与motorcar派生出摩托车(motorcycle)类。 在继承过程中,注意把vehicle设置为虚基类。如果不把vehicle设置为虚基类,会有什么问题?编程试试瞧。 5.设计people(人员)类,考虑到通用性,抽象出所有类型人员都具有得属性:number(编号)、sex(性别)、birthday(出生日期)、id(身份证号)等等。派生出student(学生)类,添加属性:班号char classNO7;从people类派生出teacher(教师)类,添加属性:职务char principalship11、部门char departmentE21。从student类中派生出graduate(研究生)类,添加属性:专业char subject21、导师teacher adviser;从graduate类与teacher类派生出TA(助教生)类,注意虚基类得使用。重载相应得成员函数,测试这些类。三、实验步骤 1、若将age设置为私有成员,在其派生类中直接给其赋值,会出现错误提示: 将age设置为公有成员时,能正常运行 代码: #includeusing namespace std;class Animalpublic:int age;class dog:public Animalpublic:int setAge(int n)age=n; return age;int maindog d;coutd、setAge(3)endl;return 0; 运行结果为:2、执行情况为:(1)基类BaseClass得构造函数; (2)派生类DerivedClass得构造函数; (3)派生类DerivedClass得析取函数; (4)基类BaseClass得析取函数; 代码: #includeusing namespace std;class BaseClasspublic:BaseClass Number=90;coutconstructor of BaseClass!endl; BaseClasscoutdestructor of BaseClass!endl;private:int Number;class DerivedClass:public BaseClasspublic: DerivedClasscoutconstrctor of DerivedClass!endl; DerivedClasscoutdestructor of DerivedClass!endl; ;int main DerivedClass der;return 0; 执行结果:3、分析:(1)执行Base得构造函数; (2)执行Derived得对象obj得Base类构造函数,并将obj(5)中参数5赋值给X及Derived类构造函数; (3)执行Derived类得对象obj得Derived得析取函数、在执行Derived类得obj得Base析取函数,最后执行与第一步相对应得Base得析取函数;执行结果:4、虚基类:使得在继承间接共同基类时只保留一份成员。 若不使用虚基类,在最终得派生类中会保留该间接共同基类数据成员得多份同名成员。 代码: #includeusing namespace std;class vehiclepublic:vehicle(float m,float w)MaxSpeed=m;Weight=w;vehiclevoid runcoutrunning of vehicle!endl;void stopcoutstopping of vehicle!endl;float MaxSpeed;float Weight;class bicycle:virtual public vehiclepublic:bicycle(float m,float w,float h):vehicle(m,w)Height=h;bicyclefloat Height;class motorcar:virtual public vehiclepublic:motorcar(float m,float w,int s):vehicle(m,w)SeatNum=s;motorcarint SeatNum;class motorcycle:public bicycle,public motorcarpublic:motorcycle(float m,float w,float h,int s):vehicle(m,w),bicycle(m,w,h),motorcar(m,w,s)motorcyclevoid displaycoutMaxSpeed=MaxSpeedendl;coutWeight=Weightendl;coutHeight=Heightendl;coutSeatNum=SeatNumendl;void mainfloat m,w,h;int s;coutm;coutw;couth;couts;motorcycle moc(m,w,h,s);moc、display;运行结果:5、代码: #include#includeusing namespace std;class Peoplepublic:People(string n,string s,string b,string i)number=n;sex=s;birthday=b;id=i;Peopleprotected:string number;string sex;string birthday;string id;class Student:virtual public Peoplepublic:Student(string n,string s,string b,string i,string c):People(n,s,b,i)classNo=c;Studentprotected: string classNo;class Teacher:virtual public Peoplepublic:Teacher(string n,string s,string b,string i,string p,string d):People(n,s,b,i)principalship=p;department=d;Teacherprotected:string principalship;/职务string department;/部门;class Graduate:public Studentpublic:Graduate(string n,string s,string b,string i,string c,string su,string t):People(n,s,b,i),Student(n,s,b,i,c)subject=su;teacher_adviser=t;Graduateprotected:string subject;/专业string teacher_adviser;/导师;class TA:public Graduate,public Teacherpublic:TA(string n,string s,string b,string i,string c,string su,string t,string p,string d):People(n,s,b,i),Graduate(n,s,b,i,c,su,t),Teacher(n,s,b,i,p,d)TAvoid displaycout编号: numberendl;cout性别: sexendl;cout生日: birthdayendl;cout身份证号: idendl;cout班级: classNoendl;cout专业: subjectendl;cout导师: teacher_adviserendl;cout导师职务: principalshipendl;cout导师部门: departmentendl;void mainstring n,s,b,i,c,su,t,p,d;cout请输入编号:n;cout请输入性别:s;cout请输入生日:b;cout请输入身份证号:i;cout请输入班级:c;cout请输入专业:su;cout请输入导师:t;cout请输入导师职务:p;cout请输入导师部门:d;TA ta(n,s,b,i,c,su,t,p,d);ta、display;运行结果:四、实验总结: 在本次操作中,前四个题操作较顺利,在做第五题时,调试改正了好久,(1)在多次派生后得初始化时,不懂得对基类进行初始化,导致编译错误;(2)在定义性别,身份证号等时,将其定义为字符型,导致输出时,全乱码,后将其改成字符串形式,输出正确;虽然在后面将其改成字符串形式输出正确,但还就是不太清楚,若用字符型,怎样才能保证不乱码,字符串与字符数组,在什么情况下,如何选择更恰当,这就是后面急需解决得问题。