C++第八章

1、

#include <iostream>

#include <cmath>

using namespace std;

double q(double,double,double);

void main()

{double a,b,c,p,x1,x2;

 cout<<"please enter a,b,c:";

 cin>>a>>b>>c;

 p=-b/(2*a);

 try

 {x1=p+q(a,b,c);

  x2=p-q(a,b,c);

  cout<<"x1="<<x1<<endl<<"x2="<<x2<<endl;

  }

 catch(double d)

  {cout<<"a="<<a<<",b="<<b<<",c="<<c<<",disc="<<d<<",error!"<<endl;}

 cout<<"end"<<endl;

}

 

double q(double a,double b,double c)

 {double disc;

 disc=b*b-4*a*c;

  if(disc<0) throw disc;

 return sqrt(disc)/(2*a);

 }

2、

#include <iostream>

#include <string>

using namespace std;

class Student

 {public:

  Student(int n,string nam)

   {cout<<"constructor-"<<n<<endl;

    num=n;name=nam;}

  ~Student(){cout<<"destructor-"<<num<<endl;}

  void get_data();

private:

  int num;

  string name;

 };

void Student::get_data()

 {if(num==0) throw num;

 else cout<<num<<" "<<name<<endl;

 cout<<"in get_data()"<<endl;

 }

 

void fun()

{Student stud1(1101,"tan");

 stud1.get_data();

 try

 {Student stud2(0,"Li");

  stud2.get_data();

  }

 catch(int n)

 {cout<<"num="<<n<<",error!"<<endl;}

}

int main()

{cout<<"mainbegin"<<endl;

 cout<<"callfun()"<<endl;

 fun();

 cout<<"main end"<<endl;

 return 0;

}

3、

#include <iostream>

using namespace std;

#include "xt8-3-h1.h"

#include "xt8-3-h2.h"

using namespace std;

using namespace student1;

 

int main()

 {Student stud1(1001,"Wang",18,"123 Beijing Road,Shanghua");

 stud1.show_data();

 student2::Student stud2(1102,"Li",'f',89.5);

 stud2.show_data();

 return 0;

 }

 

 //header1.h，文件名为xt8-3-h1.h

#include <string>

namespace student1

 {classStudent

   {public:

     Student(int n,string nam,int a,string addr)

      {num=n;name=nam;age=a;address=addr;}

     void show_data();

    private:

     int num;

     string name;

     int age;

     string address;

   };

 void Student::show_data()

   {cout<<"num:"<<num<<"  name:"<<name<<"  age:"<<age

<<"  address:"<<address<<endl;

    }

 }

 

//header2.h，文件名为xt8-3-h2.h

#include <string>

namespace student2

 {class Student

  {public:

    Student(int n,string nam,char s,float sco)

      {num=n;name=nam;sex=s;score=sco;}

    void show_data();

   private:

    int num;

    string name;

    char sex;

    float score;

   };

 

 void Student::show_data()

  {cout<<"num:"<<num<<"  name:"<<name<<"sex:"<<sex

<<"   score:"<<score<<endl; }

 }