要求打开文件"d:\file.dat",可写入数据，正确的语句是

声明一个交通工具(vehicle)基类,具有maxspeed、weight成员变量,run stop成员函数(简单输出提示“正在行进”,“停止”),同时编写vehicle类的构造函数和析构函数由此派生出自行车类(bicycle)、汽车类(motorcar),自行车类有高度(height)属性,汽车(motorcar)类有座位数(seatnum)。从bicycle和motorear派生出摩托车类(motorcycle)在继承过程中注意把vehicle设置为虚基类。

完成下面类中成员函数的定义。

#include 

#include 

using namespace std;

class str

{private:

char*st;

public:

str(char*a){set(a);}

str&operator=(__________){

delete st;

set(a.st);

return*this;}

void show(){cout<

~str(){delete st;}

void set(char*s) //初始化 st

{_____________;

strepy(st,s); }

};

void main()

{str s1"he"),s2("she");

s1show(),s2show();

s2=s1;

s1show(),s2show();

}

#include

#include 

struct Worker

{char name[15];//姓名

int age;//年龄

float pay;//工资};

void main(){

Worker x;char*t="LiWei";

int d=28;float f=9000;

strcpy(x.name,t);

x.age=d;x.pay=f;

cout<

}

.#include

using namespace std;

class B

{

public:

start(){cout<"B::s() called.\n";}

virtual~B(){cout<<"B::~start()called.\n";}

};

class E:public B

{

public:

E(int i){

cout<<"E::E()called.\n";

buf=new char[i];}

virtual~E()

{

delete[]buf;

cout<<"E::~E()called.\n";

}

private:

char*buf;

};

void fun(B*a)

cout<<"fun()called.\n";

delete a;

}

void main()

{

B*a=new E(15);

fun(a);

}

用带有默认参数的函数实现求前两个及三个正整数中的最大数。

#include 

using namespace std;

int main()

{int max(int a,int b,int c=0); 

int a,b,c,m1,m2;

cin>>a>>b>>C:

____________

m2=max(a,b);__________

cout<<"a,b,c三个正整数中的最大数为:"<

cout<"a,b两个正整数中的最大数为:"<

return 0;

}

intmax(int a,int b,int c)

{if(b>a)a=b;

____________

return a;

}

程序实现大写字母转换成小写字母。 

#include 

void main()

{char a ;

______________;

cin>>a;

if(______________)

a=a+i:

cout<

}

程序完成后的运行结果为:DERIVEDBASE 

#include 

class BASE{

public:

~BASE(){__________}

};

class DERIVED:public BASE{

public:

~DERIVED(){cout<<"DERIVED";}

};

void main()

{__________}

程序完成后的运行结果为:*＄*＄# 

#include 

using namespace std;

int main()

{int i;

for(i=3;i<=6;i++)

{if(i%3)___________;

else continue;

___________

cout<<"#\n"; 

return 0;

}

#include 

using namespace std;

class CTest

{private: 

int x;

public:

CTest(int x)

{this->x=x;}

int getX()

{retunx;}

};

int main()

{const CTest obj(5);

 cout<

retum0;

}

下面的程序在VC6.0上编提示error C2440: 'type cast' :cannot convert from 'class Complex'to 'float',No user-defined-conversion operator available that can perform. this conversion 

#include 

using namespace std; 

class Complex{

public:

Complex(float r=0,float i=0)

{real=r;imag=i;}

void print()

{cout<'('<

private:

float real,imag;

};

int main()

{Complex a(2.2f,4.4f);

a.print();

cout<

return 0;

}