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标题: [求助]学继承,发现了个严重的问题,不知道哪错了,大家来看看 [打印本页]

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作者: 缘分天空    时间: 2009-11-4 01:27
标题: [求助]学继承,发现了个严重的问题,不知道哪错了,大家来看看
//这是我看书上的例题改的,原来的程序没有重载>>,没有数据输入函数;
//我改了后问题就出来了....我>>函数居然不能访问类里的数据成员,至少出错提示是这么说的"cannot access......"
//编译器VC6.0
#include <iostream>
#include <string>
using namespace std;
class Student //声明基类
{
public: //基类公用成员
void display( );
friend istream& operator >>(istream& in,Student& stu);
protected : //基类保护成员
int num;
string name;
char sex;
};
void Student::display( )
{
cout<<"num: "<<num<<endl;
cout<<"name: "<<name<<endl;
cout<<"sex: "<<sex<<endl;
}
istream& operator >>(istream& in,Student& stu)
{
cout<<"Please input the num,name,and sex: \n";
in>>stu.num>>stu.name>>stu.sex;
return in;
}

class Student1: protected Student //用protected继承方式声明一个派生类
{
public:
void display1( );
friend istream& operator >>(istream& in,Student1& stu);//这里该过来了,谢谢楼下提醒,不过错误提示还是没变;
private:
int age;
string addr;
};
void Student1::display1( )
{
cout<<"num: "<<num<<endl; //引用基类的保护成员
cout<<"name: "<<name<<endl;
cout<<"sex: "<<sex<<endl;
cout<<"age: "<<age<<endl; //引用派生类的私有成员
cout<<"address: "<<addr<<endl;
}
istream& operator >>(istream& in,Student1& stu)
{
cout<<"Please input the num,name,sex,age,and address:\n";
in>>stu.num>>stu.name>>stu.sex>>stu.age>>stu.addr;
return in;
}
int main( )
{
Student1 stud1; //stud1是派生类student1的对象
cout<<"input the student's record:\n";
cin>>stud1;
stud1.display1( ); //display是派生类中的公用成员函数
return 0;
}

--------------------------------------传说中的分割线-------------------------------------------
这里的错误提示:

Compiling...
C5-3.CPP
E:\C++源代码\教材例题程序\C5\C5-3.CPP(25) : error C2248: 'num' : cannot access protected member declared in class 'Student'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(10) : see declaration of 'num'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(25) : error C2248: 'name' : cannot access protected member declared in class 'Student'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(11) : see declaration of 'name'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(25) : error C2248: 'sex' : cannot access protected member declared in class 'Student'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(12) : see declaration of 'sex'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(50) : error C2248: 'num' : cannot access protected member declared in class 'Student'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(10) : see declaration of 'num'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(50) : error C2248: 'name' : cannot access protected member declared in class 'Student'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(11) : see declaration of 'name'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(50) : error C2248: 'sex' : cannot access protected member declared in class 'Student'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(12) : see declaration of 'sex'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(50) : error C2248: 'age' : cannot access private member declared in class 'Student1'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(35) : see declaration of 'age'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(50) : error C2248: 'addr' : cannot access private member declared in class 'Student1'
E:\C++源代码\教材例题程序\C5\C5-3.CPP(36) : see declaration of 'addr'
执行 cl.exe 时出错.
C5-3.OBJ - 1 error(s), 0 warning(s)

谁告诉一下怎么错了?还有,对代码有什么意见都说出来哈,

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作者: 瘋子愛老婆    时间: 2009-11-4 01:27
今天下午没课,晚上也没课,我在线等:>

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作者: 发指的青春    时间: 2009-11-4 01:27

1. #include <iostream>
   
2. #include <string>
   
3. using namespace std;
   
4. 
   
5. class Student
   
6. {
   
7. public:
   
8. void display( );
   
9. friend istream& operator >>(istream& in,Student& stu);
   
10. protected :
    
11. int num;
    
12. string name;
    
13. char sex;
    
14. };
    
15. 
    
16. void Student::display( )
    
17. {
    
18. cout<<"num: "<<num<<endl;
    
19. cout<<"name: "<<name<<endl;
    
20. cout<<"sex: "<<sex<<endl;
    
21. }
    
22. 
    
23. istream& operator >>(istream& in,Student& stu)
    
24. {
    
25. cout<<"Please input the num,name,and sex: \n";
    
26. in>>stu.num>>stu.name>>stu.sex;
    
27. return in;
    
28. }
    
29. 
    
30. class Student1: protected Student
    
31. {
    
32. public:
    
33. void display1( );
    
34. friend istream& operator >>(istream& in,Student1& stu);
    
35. private:
    
36. int age;
    
37. string addr;
    
38. };
    
39. 
    
40. void Student1::display1( )
    
41. {
    
42. cout<<"num: "<<num<<endl;
    
43. cout<<"name: "<<name<<endl;
    
44. cout<<"sex: "<<sex<<endl;
    
45. cout<<"age: "<<age<<endl;
    
46. cout<<"address: "<<addr<<endl;
    
47. }
    
48. 
    
49. istream& operator >>(istream& in,Student1& stu)
    
50. {
    
51. cout<<"Please input the num,name,sex,age,and address:\n";
    
52. cout<<"num = ";
    
53. in>>stu.num;
    
54. cout<<"name = ";
    
55. in>>stu.name;
    
56. cout<<"sex('m' or 'w') = ";
    
57. in>>stu.sex;
    
58. cout<<"age = ";
    
59. in>>stu.age;
    
60. cout<<"address = ";
    
61. getchar();
    
62. 
    
63. getline(in, stu.addr);
    
64. return in;
    
65. }
    
66. 
    
67. int main( )
    
68. {
    
69. Student1 stud1;
    
70. cout<<"input the student's record:\n";
    
71. cin>>stud1;
    
72. stud1.display1( );
    
73. return 0;
    
74. }

复制代码

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作者: 皇家㊣贺v    时间: 2009-11-4 01:27
恩?版主,你改了之后还是同样的错误...

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作者: 飞.逝﹏..    时间: 2009-11-4 01:27
不过你写的代码让我看的舒服...呵呵

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作者: 金马    时间: 2009-11-4 01:27
你用gcc 编译吧．　如果不会gcc, 到我的博克去看　all about C++

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作者: ︶ぺ雨湮ㄣ    时间: 2009-11-4 01:27
为什么会"cannot access protected member declared in class 'Student'"呢?啊...为什么.

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作者: 炫夜    时间: 2009-11-4 01:27
哦,我先去装一下GCC

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作者: 云-飘天涯    时间: 2009-11-4 01:27

class Student1: protected Student //用protected继承方式声明一个派生类
{
public:
void display1( );
friend istream& operator >>(istream& in,Student& stu);
private:
int age;
string addr;
};

改成：

1. 
   
2. class Student1: protected Student //用protected继承方式声明一个派生类
   
3. {
   
4. public:
   
5. void display1( );
   
6. friend istream& operator >>(istream& in,Student1& stu);
   
7. private:
   
8. int age;
   
9. string addr;
   
10. };
    

复制代码

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作者: 我和老公在    时间: 2009-11-4 01:27
回楼上:
版主的那段代码跟你的是一样的,一模一样;输出的结果和我写的出错提示是一样的;还是说不能访问那些数据成员;
还有,GCC我用不来...谁有GCC的帮我编译一下看看是编译器的问题还是我代码的问题;谢谢了;
我真是看不出来怎么就错了;

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