派生类与继承

1、下面的程序可以输出ASCII字符与所对应的数字的对照表。修改下列程序，使其可以输出字母a到z（或任意两个字符间）与所对应的数字的对照表。

class table

{

public:

table(int p)

{

i=p;

}

void ascii(void);

protected:

int i;

};

void table::ascii(void)

{

int k=1;

for (;i<127;i++)

{

cout<<setw(4)<<i<<" "<<(char)i;

if((k)%12==0)

cout<<"\n";

k++;

}

cout<<"\n";

}

class der_table:public table

{

public:

der_table(int p,char *m):table(p)

{

c=m;

}

void print(void);

protected:

char *c;

};

void der_table::print(void)

{

cout<<c<<"\n";

table::ascii();

}

int main()

{

der_table obl(32,"ASCII value---char");

obl.print();

return 0;

}

提示：修改后的主程序为：

int main()

{

der_table ob('a','z',"ASCII value---char");

ob.print();

return 0;

}

#include<iostream>

#include<iomanip>

using namespace std;

class table

{

protected:

int i;

int j;

public:

table(int p,int q)

{

i=p;

j=q;

}

void ascii()

{

int k=1;

for(;i<=j;i++)

{

cout<<setw(4)<<i<<" "<<(char)i;

if((k)%12==0)

cout<<endl;

k++;

}

cout<<endl;

}

};

class der_table:public table

{

protected:

char *c;

public:

der_table(int p,int q,char *m):table(p,q)

{

c=m;

}

void print()

{

cout<<c<<endl;

table::ascii();

}

};

int main()

{

der_table ob('a','z',"ASCII value---char");

ob.print();

return 0;

}

2、已有类Time和Date，要求设计一个派生类Birthtime，它继承类Time和Date，并且增加一个数据成员Childname用于表示小孩的名字，同事设计主程序显示一个小孩的出生时间和名字。

class Time

{

public:

Time(int h,int m, int s)

{

hours=h;

minutes=m;

seconds=s;

}

void display()

{

cout<<"出生时间："<<hours<<"时"<<minutes<<"分"<<seconds<<"秒"<<endl;

}

protected:

int hours,minutes,seconds;

};

class Date

{

public:

Date(int m,int d,int y)

{

month=m;

day=d;

year=y;

}

void display()

{

cout<<"出生年月："<<year<<"年"<<month<<"月"<<day<<"日"<<endl;

}

protected:

int month,day,year;

};

#include<iostream>

#include<string>

using namespace std;

class time

{

protected:

int hours,minutes,seconds;

public:

time(int h,int m,int s)

{

hours=h;

minutes=m;

seconds=s;

}

void display()

{

cout<<"出生时间："<<hours<<"时"<<minutes<<"分"<<seconds<<"秒"<<endl;

}

};

class date

{

protected:

int month,year,day;

public:

date(int m,int d,int y)

{

month=m;

day=d;

year=y;

}

void display()

{

cout<<"出生年月"<<year<<"年"<<month<<"月"<<day<<"日"<<endl;

}

};

class birthtime:public time,public date

{

private:

string childname;

public:

birthtime(int h,int m,int s,int m1,int d,int y,string n):time(h,m,s),date(m1,d,y)

{

childname=n;

}

void display()

{

time::display();

date::display();

cout<<"名字是："<<childname<<endl;

}

};

int main()

{

birthtime a(0,6,33,6,29,2000,"jassic");

a.display();

return 0;

}

3、编写一个学生和教师的数据输入和显示程序。学生数据有编号、姓名、性别、年龄、系别和成绩，教师数据有编号、姓名、性别、年龄、职称和部门。要求将编号、姓名、性别、年龄的输入和显示设计成一个类Person，并作为学生类Student和教师类Teacher的基类。

#include<iostream>

#include<string>

using namespace std;

class person

{

private:

int num;

string name;

public:

person(int n,string na)

{

cout<<"putin the num:";

cin>>n;

num=n;

cout<<endl<<"putin the name:";

cin>>na;

name=na;

}

void show()

{

cout<<"the name is:"<<name<<endl<<"the number is:"<<num<<endl;

}

};

class student:public person

{

private:

int classnum;

float score;

public:

student(int n,string na,int cn,float s):person(n,na)

{

cout<<"please putin the classnum:";

cin>>cn;

cout<<endl<<"please putin the score:";

classnum=cn;

cin>>s;

score=s;

}

void show1()

{

show();

cout<<"the classnumber is:"<<classnum<<endl<<"the score is:"<<score<<endl;

}

};

class teacher:public person

{

private:

string title;

string depart;

public:

teacher(int n,string na,string t,string d):person(n,na)

{

cout<<"please putin the title:";

cin>>t;

title=t;

cout<<endl<<"please putin the department:";

cin>>d;

depart=d;

}

void show2()

{

show();

cout<<"the title is :"<<title<<endl<<"the department is:"<<depart<<endl;

}

};

int main()

{

int m,cln;

string n;

float sc;

student s(m,n,cln,sc);

s.show1();

string t;

string d;

teacher te(m,n,t,d);

te.show2();

return 0;

}

4、给出下面的基类：

class area

{

protected:

double height;

double width;

public:

area(double h,double w)

{

height=h;

width=w;

}

virtual double getarea()=0;

};

【要求】

（1）建立基类area的俩个派生类rectangle与isosceles，让每一个派生类都包含一个函数getarea()，分别用来返回矩形与三角形的面积。用构造函数对height与width进行初始化。

（2）写出主程序，用来求height与width分别为10.0与5.0的矩形面积，以及求height与width分别为4.0与6.0的三角形面积。

（3）要求通过使用基类指针访问虚函数的方法（即运行时的多态性）分别求出矩形和三角形面积。

#include<iostream>

using namespace std;

class area

{

protected:

double height;

double width;

public:

area(double h,double w)

{

height=h;

width=w;

}

virtual double getarea()=0;

};

class rectangle:public area

{

private:

double a;

public:

rectangle(double a,double b):area(a,b)

{}

virtual double getarea()

{

a=height*width;

return a;

}

};

class isosceles:public area

{

private:

double a;

public:

isosceles(double a,double b):area(a,b)

{}

virtual double getarea()

{

a=0.5*height*width;

return a;

}

};

int main()

{

area *mp;

rectangle r(10.0,5.0);

mp=&r;

cout<<"the area of rectangle is:"<<mp->getarea()<<endl;

isosceles i(4.0,6.0);

mp=&i;

cout<<"the area of isosceles is:"<<mp->getarea()<<endl;

return 0;

}

5、编写一个程序，递归调用被继承的基类成员函数，实现求素数的功能。

#include<iostream>

using namespace std;

class base

{

private:

int x;

public:

base(int p)

{

x=p;

}

int fun(int j)

{

int t=2,f=1;

for(;t<j&&f==1;t++)

{

if(j%t==0)

f=0;

return f;

}

}

};

class derive:public base

{

protected:

char *c;

public:

derive(char *m):base(2)

{

c=m;

}

int fun1(int l)

{

return base::fun(l);

}

};

int main()

{

derive a("base\n");

int n;

cout<<"please input a int :";

cin>>n;

if(a.fun1(n)==1)

cout<<n<<"is prime number"<<endl;

else

cout<<n<<"is not prime number"<<endl;

return 0;

}