下面程序中Base是抽象类。请在下面程序的横线处填上适当内容，以使程序完整，并使程序的输出为：Der1 called!

Der2 called!

#include ﹤ iostream. h﹥

class Base

{ public:

_________;

};

class Der1: public Base

{ public:

void display( ) { cout ﹤﹤"Der1 called! "﹤﹤endl; }

};

class Der2: public Base

{ public:

void display( ) { cout ﹤﹤"Der2 called! "﹤﹤endl; }

};

void fun( _________ )

{ p-﹥display( ); }

void main( )

{ Der1 b1;

Der2 b2;

Base * p=&b1;

fun(p);

p=&b2;

fun(p);

}

定义一个图形类(figure)，其中有保护类型的成员数据：高度(height)和宽度(width)，一个公有的构造函数。由该图形类建立两个派生类：矩形类和等腰三角形类。在每个派生类中都包含一个函数area( )，分别用来计算矩形和等腰三角形的面积。其中，主函数已给出，请完成其他部分的代码。

int main( )

{

triangle tri(2, 3);

rectangle rec(2, 3);

cout ﹤﹤"The area of triangle is: "﹤﹤ tri. area( )﹤﹤endl;cout ﹤﹤"The area of rectangle is: "﹤﹤rec. area( )﹤﹤ endl;return 0;

}

#include ﹤iostream﹥

using namespace std;

class CBase

{

public:

void fun( );

};

void CBase:: fun( )

{cout﹤﹤"调用基类类的函数fun( )\n";}

class CDerived:

public CBase

{public:void fun( );

};

void CDerived:: fun( )

{ cout﹤﹤"调用派生类的函数fun( )\n”;

}

void main( )

{

CDerived d1;

CBase *pd=&d1;

CBase &pd=d1;

d1. fun( );

pb-﹥fun( );

pd.fun( );

}

#include ﹤iostream﹥

using namespace std;

int a[ ]={2,4,6,7,10};

int &index( int i)

{ retum a[i]; }

void main( ) {

int i;

_________

 //调用 index函数，将数组a中的元素7替换为8

for( _________ ) //输出数组a

cout﹤﹤a[i]﹤﹤" ";

}

#include ﹤iostream﹥

#include ﹤strinh﹥

#include ﹤iomanip﹥

using namespace std;

class student

{

char name[ 8];

int deg;

char level[7];

friend class process; //说明友元类

public:

student( char na[ ],

 int d)

{

strcpy(name,na);

deg=a;

}

};

class process

{

public:

void trans( student &s)

{

int i=s. deg/10;

switch(i)

{

case 9:

strcpy(s. level, "优"); break;

case 8:

stecpy(s. level, "良"); break;

case 7:

strcpy(s. level, "中"); break;

case 6:

strcpy(s. level, "及格");

break;default:

strcpy(s. level, "不及格"); break;

}

}

void show( student &s)

{cout ﹤﹤setw(10)﹤﹤s.name﹤﹤setw(4)﹤﹤s. deg﹤﹤ setw(8)﹤﹤s.level﹤﹤ endl;}

};

void main( )

{student st[ ]={ student("Jack", 78), student ("Lucy",92),student("Lily", 62), student("Tom", 99 )};

process p;

cout﹤﹤"结果:"﹤﹤"姓名"﹤﹤setw(6)﹤﹤"成绩"﹤﹤sew(8)﹤﹤"等级"﹤﹤endl;

for(int i=0; i ﹤4;i++)

{

p. trans(st[i]);

p. show(st[i]);

}

}

任意输入10个同学的成绩,计算其平均成绩。要求用函数average( )计算平均成绩。主函数输入数据并输出结果。

#include "stdafx.h"

#include ﹤iostream﹥

using namespace std;

void main(void)

{

float average(float a[ ]);

float score[10];

for( _________ )

{

cin﹥﹥score[i];

}

cout ﹤﹤"average: "﹤﹤ average( score)﹤﹤endl;

}

float average( float a[ ])

{

float sum =0;

for( int i=0; i﹤10; i ++)

{

_________

}

return (sum/10);

}

下面程序中Base是抽象类。请在下面程序的横线处填上适当内容，以使程序完整，并使程序的输出为：Der1 called!

Der2 called!

#include ﹤ iostream. h﹥

class Base

{ public:

_________;

};

class Der1: public Base

{ public:

void display( ) { cout ﹤﹤"Der1 called! "﹤﹤endl; }

};

class Der2: public Base

{ public:

void display( ) { cout ﹤﹤"Der2 called! "﹤﹤endl; }

};

void fun( _________ )

{ p-﹥display( ); }

void main( )

{ Der1 b1;

Der2 b2;

Base * p=&b1;

fun(p);

p=&b2;

fun(p);

}

完成下面类中成员函数的定义。

#include ﹤iostream﹥

#include ﹤string﹥

using namespace std;

class str

{ private:

char * st;

public:

str(char *a)

{

set (a);

}_________ //运算符“=”重载函数

{

delete st;set(a.st);

return * this;

}

void show( )

{

cout ﹤﹤ st ﹤﹤ endl;

 }

~str( )

 { delete st; }

void set(char *s);

{

_________strcpy( st, s);

}

};

void main( );

{

str s1("hello"),

s2("world");

s1. show( ),

s2.show( );

s2=s1;

s1. show( ),

s2.show( );

}

Test_Static类内有一静态成员变量num，且初始值设为15。

#include ﹤iostream﹥

using namespace std;

class Test_Static

{

private:_________

public:

Test_Static(int);void print( );

};_________

Test_Static:: Test_Static(int n)

{

num=n;

}

void Test_Static:: print( )

{

cout﹤﹤num﹤﹤endl;

}

void main( )

{

Test_Static ts(10);ts.print( );

}

#include ﹤iostream﹥

using namespace std;

int main( )

 {

int a= 10;

int *p1=NULL;

int *p2=a;

cout ﹤﹤p1﹤﹤*p2﹤﹤endl;

return 0;

}

#include ﹤iostream﹥

using namespace std;

void main( )

{

int x1(3), x2(8);

int * const p =&x1;

cout ﹤﹤*p﹤﹤ endl;

p=&x2;

cout ﹤﹤*p﹤﹤ endl;

}